appendix

Anatomy

The vermiform appendix is present only in humans, certain anthropoid apes and the wombat (a nocturnal, burrowing Australian marsupial). It isa blind muscular tube with mucosal, submucosal, muscular and serosal layers. Morphologically, it is the undeveloped distal end of the large caecum found in many lower animals. At birth, the appendix is short and broad at its junction with the caecum, but differential growth of the caecum produces the typical tubular structure by about the age of 2 years (Condon). During childhood, continued growth of the caecum commonly rotates the appendix into a retrocaecal but intraperitoneal position (Fig. 1).

Figure 1 : appendix relationship with other organ, cecum, ileum,mesoappendix

In approximately a quarter of cases, rotation of the appendix does not occur resulting in a pelvic, suhcaecal or paracaecal position. Occasionally, the tip of the appendix becomes extraperitoneal lying behind the caecum or ascending colon. Rarely, the caecum does not migrate during development to its normal position in the right lower quadrant of the abdomen. In these circumstances the appendix can be found near the gall bladder or, in the case of situs inversus viscerum, in the left iliac fossa causing diagnostic difficulty if appendicitis develops (Fig. 2, 3).

Figure 2 show type of appendix correlate with tip of appendix

Figure 3 show variation in position of appendix

The position of the base of the appendix is constant, being found at the confluence of the three taeniae coli of the caecum which fuse to form the outer longitudinal muscle coat of the appendix. At operation, use can he made of this to find an elusive appendix, as gentle traction on the taeniae coli, particularly the anterior taenia, will lead the operator to the base of the appendix.
The mesentcry of the appendix or mesoappendix arises from the lower surface of the mesentery of the terminal ileum, and itself is subject to great variation. Sometimes as much as the distal third of the appendix is bereft of mesoappendix. Especially in childhood, the mesoappendix is so transparent that the contained blood vessels can he seen (Fig. 4).

Figure 4 show artery supply appendix, appendiceal artery, branch of ileocolic artery.

In many adults it becomes laden with fat, which obscures these vessels. The appendicular artery, a branch of the lower division of the ileocolic artery, passes behind the terminal ileum to enter the mesoappendix a short distance from the base of the appendix. It then comes to lie in the free border of the mesoappendix. An accessory appendicular artery may be present but, in most people, the appendicular artery is an ‘end-artery’, thrombosis of which results in necrosis of the appendix (syn. gangrenous appendicitis). Four, six or more lymphatic channels traverse the mesoappendix to empty into the ileocaecal lymph nodes.

Microscopic anatomy

The appendix varies considerably in length and circumference. The average length is between 7.5 and 10 cm. The lumen is irregular, being encroached upon by multiple longitudinal folds of mucous membrane lined by columnar cell intestinal mucosa of colonic type (Fig. 5).

Figure 5 show microscopic anatomy of appendix.

Crypts are present but are not numerous. In the base of the crypts lie argentaffln cells (Kultschitzsky cells) which may give rise to carcmnoid tumours (vide in Ira). The appendix is the most frequent site for carcinoid tumours which may present with appendicitis due to occlusion of the appendiceal lumen.
The submucosa contains numerous lymphatic aggregations or follicles. This profusion of lymph tissue has promoted the concept that the appendix is the human equivalent of the avian bursa of Fabricius as a site of maturation of thymus-independent lymphocytes. While no discernible change in immune function results from appendicectomy, the prominence of lymphatic tissue in the appendix of young adults seems important in the aetiology of appendicitis (vide infra).

Acute appendicitis

While there are isolated reports of perityphlitis (fatal inflammation of the caecal region) from the late 1500s, recognition of acute appendicitis as a clinical entity is attributed to Reginald Fitz who presented a paper to the first meeting of the Association of American Physicians in 1886 entitled ‘Perforating inflammation of the vermiform appendix’. Soon afterwards Charles McBurney described the clinical manifestations of acute appendicitis including the point of maximum tenderness in the right iliac fossa that since bears his name. The incidence of appendicitis seems to have risen greatly in the first half of the twentieth century, particularly in Europe, America and Australasia, with up to 16 per cent of the population undergoing appendicectomy. In the past 30 years the incidence has fallen dramatically in these countries, with the number of operations in England and Wales declining from 113 000 in 1966 to 48 000 in 1990. In developing countries, which are adopting a more refined Western-type diet, the incidence continues to rise. No reason has been established for these changes in the incidence of acute appendicitis.
Acute appendicitis is relatively rare in infants, and becomes increasingly common in childhood and early adult life, reaching a peak incidence in the teens and early 20s. After middle age the risk of developing appendicitis in the future is quite small. The incidence of appendicitis is equal amongst males and females before puberty. In teenagers and young adults the male:female ratio increases to 3:2 at the age of 25 years, thereafter the greater incidence in males declines.

Aetiology

There is no unifying hypothesis regarding the aetiology of acute appendicitis. While appendicitis is clearly associated with bacterial proliferation within the appendix, no single organism is responsible, indeed a mixed growth of aerobic and anaerobic organisms is usual. The initiating event causing bacterial proliferation is controversial. Obstruction of the appendix lumen has been widely held to be important, and indeed some form of luminal obstruction by either a faecolith or stricture is found in the majority of cases. A faecolith is composed of inspissated faecal material, calcium phosphates, bacteria and epithelial debris. Rarely a foreign body is incorporated into the mass. The incidental finding of a faecolith is a relative indication for prophylactic appendicectomy.

A fibrotic stricture of the appendix usually indicates previous appendicitis which resolved without surgical intervention. Obstruction of the appendiceal orifice by tumour, particularly carcinoma of the caecum, is an occasional cause of acute appendicitis in middle age and the elderly. Intestinal parasites, particularly Oxyuris vermicularis (syn. pinworm), can proliferate in the appendix and occlude the lumen.

Pathology

Obstruction of the appendiceal lumen seems to be essential for development of appendiceal gangrene and perforation. Yet, in many cases of early appendicitis the appendix lumen is patent despite the presence of mucosal inflammation and lymphoid hyperplasia. Occasional clustering of cases amongst children and young adults suggests an infective agent, possibly viral, which initiates an inflammatory response, which within the narrow lumen of the appendix leads to luminal obstruction. Once obstruction occurs, continued mucus secretion and inflammatory exudation increase intraluminal pressure, obstructing lymphatic drainage. Oedema and mucosal ulceration develop with bacterial translocation to the submucosa. Resolution may occur at this point either spontaneously or in response to antibiotic therapy. Where the condition progresses, further distension of the appendix may cause venous obstruction and ischaemia of the appendix wall. With ischaemia, bacterial invasion occurs through the muscularis propria and submucosa producing acute appendicitis.

Finally, ischaemic necrosis of the appendix wall produces gangrenous appendicitis, with free bacterial contamination of the peritoneal cavity. Alternatively, the greater omentum and loops of small bowel become adherent to the inflamed appendix, walling off the spread of peritoneal contamination resulting in a phlegmonous mass or paracaecal abscess. Rarely, appendiceal inflammation resolves leaving a distended mucus-filled organ termed a mucocele of the appendix.

It is the potential for peritonitis that is the great threat of acute appendicitis. Peritonitis occurs as a result of free migration of bacteria through an ischaemic appendicular wall, through frank perforation of a gangrenous appendix or delayed perforation of an appendix abscess. Factors which promote this process include extremes of age, immunosuppression, diabetes mellitus, faecolith obstruction of the appendix lumen, a free-lying pelvic appendix and previous abdominal surgery which limits the ability of the greater omentum to wall off the spread of peritoneal contamination.

In these situations a rapidly deteriorating clinical course is accompanied by signs of diffuse peritonitis and systemic sepsis syndrome.

Clinical diagnosis — history

The classical features of acute appendicitis begin with poorly localised colicky abdominal pain.
This is due to midgut visceral discomfort in response to appendiceal inflammation and obstruction. The pain is frequently first noticed in the periumbilical region and is similar to, but less intense than, the colic of small bowel obstruction. Central abdominal pain is associated with anorexia, nausea and usually one or two episodes of vomiting which follow the onset of pain (Murphy). Anorexia is a useful and constant clinical feature, particularly in children. The patient often gives a history of similar discomfort which settled spontaneously.
With progressive inflammation of the appendix, the parietal peritoneum in the right iliac fossa becomes irritated producing more intense, constant and localised somatic pain which begins to predominate. This is often reported by the patient as an abdominal pain which has shifted and changed in character. Typically, coughing or sudden movement exacerbates the right iliac fossa pain.
The classical visceral—somatic sequence of pain is present in only about half those patients subsequently proven to have acute appendicitis. Atypical presentations include pain which is predominantly somatic or visceral and poorly localised. Atypical pain is more common in the elderly in whom localisation to the right iliac fossa is unusual. An inflamed appendix in the pelvis may never produce somatic pain involving the anterior abdominal wall, but may instead cause suprapubic discomfort and tenesmus. In this circumstance, tenderness may only be elicited on rectal examination and is the basis for the recommendation that a rectal examination should be performed on every case of lower abdominal pain.
During the first 6 hours there is rarely any alteration in temperature or pulse rate. After that time, slight pyrexia (37.2—37.70C) with corresponding increase in the pulse rate to 80 or 90 is usual. However, in 20 per cent of cases there is no pyrexia or tachycardia in the early stages. In children a temperature greater than 38.50C suggests other causes, for example mesenteric adenitis (vide in Ira).
Typically, two clinical syndromes of acute appendicitis can be discerned, acute catarrhal (nonobstructive) appendicitis and acute obstructive appendicitis. The latter is characterised by a much more acute course. The onset of symptoms is abrupt and there may be generalised abdominal pain from the start. The temperature may be normal and vomiting is common, so that the clinical picture may mimic acute intestinal obstruction. Once recognised, urgent surgical intervention is required because of the more rapid progression to perforation.

Clinical diagnosis — signs

The diagnosis of appendicitis rests more on thorough clinical examination of the abdomen than on any aspect of the history or laboratory investigation. The cardinal features are those of an unwell patient with low grade pyrexia, localised abdominal tenderness, muscle guarding and rebound tenderness. Inspection of the abdomen may show limitation of respiratory movement in the lower abdomen. The patient is then asked to point to where the pain began and to where it moved (the pointing sign). Gentle superficial palpation of the abdomen, beginning in the left iliac fossa moving anticlockwise to the right iliac fossa, will detect muscle guarding over the point of maximum tenderness, classically McBurney point. Asking the patient to cough or gentle percussion over the site of maximum tenderness will elicit rebound tenderness.
Deep palpation of the left iliac fossa may cause pain in the right iliac fossa (Rovsing’s sign), which is helpful in supporting a clinical diagnosis of appendicitis. Occasionally an inflamed appendix lies on the psoas muscle and the patient, often a young adult, will lie with the right hip flexed for pain relief (the psoas sign). Spasm of the obturator internus is sometimes demonstrable when the hip is flexed and internally rotated. If an inflamed appendix is in contact with the obturator internus, this manoeuvre will cause pain in the hypogastrium (the obturator test) (Zachary Cope). Cutaneous hyperaesthesia may be demonstrable in the right iliac fossa, hut is rarely of diagnostic value.

Special features, according to position of the appendix

Retrocaecal

Rigidity is often absent and even on deep pressure tenderness may he lacking (silent appendix), the reason being that the caecum, distended with gas, prevents the pressure exerted by the hand from reaching the inflamed structure. However, deep tenderness is often present in the loin, and rigidity of the quadratus lumborum may he in evidence. Psoas spasm, due to the inflamed appendix being in contact with that muscle, may he sufficient to cause flexion of the hip joint. Hyperextension of the hip joint may induce abdominal pain when the degree of psoas spasm is insufficient to cause flexion of the hip.

Pelvic

Occasionally early diarrhoea results from an inflamed appendix being in contact with the rectum. When the appendix lies entirely within the pelvis there is usually complete absence of abdominal rigidity, and often tenderness over McBurney’s point is lacking as well. In some instances deep tenderness can he made out just above and to the right of the symphysis pubis. In either event, a rectal examination reveals tenderness in the rectovesical pouch or the pouch of Douglas, especially on the right side. Spasm of the psoas and obturator internus muscles may he present when the appendix is in this position. An inflamed appendix in contact with the bladder may cause frequency of micturition.

Post ileal

Although this is rare, it accounts for some of the cases of missed appendix’. Here the inflamed appendix lies behind the terminal ileum. It presents the greatest difficulty in diagnosis because the pain may not shift, diarrhoea is a feature and marked retching may occur. Tenderness, if any, is ill-defined, although it may he present immediately to the right of the umbilicus.

Special features, according to age

Infants

Appendicitis is relatively rare in infants under 36 months of age and for obvious reasons the patient is unable to give a history. Because of this, diagnosis is often delayed and thus the incidence of perforation and postoperative morbidity is considerably higher than in older children. Diffuse peritonitis can develop rapidly due to the underdeveloped greater omentum, which is unable to give much assistance in localising the infection.

Children

It is rare to find a child with appendicitis who has not vomited. Children with appendicitis usually have complete aversion to food. In addition, they do not sleep during the attack and very often bowel sounds are completely absent in the early stages.

The elderly

Gangrene and perforation occur much more frequently in elderly patients. Elderly patients with lax abdominal walls or obesity may harbour a gangrenous appendix with little evidence of it, and the clinical picture may simulate subacute intestinal obstruction. These features coupled with coincident medical conditions produce a much higher mortality for acute appendicitis in the elderly.

The obese

Obesity can obscure and diminish all the local signs of acute appendicitis. Delay in diagnosis coupled with the technical difficulty of operating in the obese make it wiser to consider operating through a midline abdominal incision

Pregnancy

Appendicitis is the most common extra uterine acute abdominal condition in pregnancy with a frequency of from one in 1500 to one in 2000 pregnancies. Diagnosis is complicated by delay in presentation; early nonspecific symptoms are often attributed to the pregnancy, and the changing location of the appendix during pregnancy. As pregnancy develops during the second and third trimesters, the caecum and appendix are progressively pushed to the right upper quadrant of the abdomen. This displacement can result in flank or back pain, and may be confused with pyelonephritis, while lower abdominal pain may be confused with torsion of an ovarian cyst. Foetal loss occurs in 3—5 per cent of cases, increasing to 20 per cent if perforation is found at operation.

Differential diagnosis

Although acute appendicitis is the most common abdominal surgical emergency, the diagnosis at times can be extremely difficult. It is important to remember that many conditions which mimic appendicitis also require surgical intervention, or if they do not are rarely made worse by appendicectomy. However, there is a number of common conditions that it is wise to consider carefully and, where possible, exclude. The differential diagnosis differs in patients of different ages and in adult life, females have the added differential of diseases of the female genital tract (Table 59.5).

Children

The diseases most commonly mistaken for acute appendicitis are acute gastroenteritis and mesenteric lymphadenitis. In acute gastroenteritis there is intestinal colic together with diarrhoea and vomiting, but localised tenderness does not usually occur. There is often a history of other family members being affected. Post ileal appendicitis may mimic this condition, thus hospital admission and careful observation are warranted. Where serious doubt persists laparoscopy or surgical exploration may be indicated. In mesenteric lymphadenitis, the pain is colicky in nature and the patient may be completely free from pain between attacks, which last for a few minutes. Cervical lymph nodes may be enlarged. If present, shifting tenderness when the child turns on to his or her left side is convincing evidence. The condition presents a common diagnostic difficulty in children and if doubt exists exploration is advisable.
It may be impossible clinically to distinguish Meckel’s diverticulitis from acute appendicitis. The pain is similar, however signs may be central or left-sided. Occasionally, there is a history of antecedent abdominal pain or anaemia.
It is important to distinguish between acute appendicitis and intussusception.Appendicitis is uncommon before the age of 2 years, whereas the median age for intussusception is 18 months. A mass may be palpable in the right lower quadrant and the preferred treatment of intussusception is reduction by careful barium enema.

Henoch—Schönlein purpura

This is often preceded by a sore throat or respiratory infec­tion. Abdominal pain can be severe and be confused with intussusception or appendicitis. There is nearly always an ecchymotic rash, typically affecting the extensor surfaces of the limbs and on the buttocks. The face is usually spared. The platelet count and bleeding time are within normal limits.

Lobar pneumonia and pleurisy

Lobar pneumonia and pleurisy, especially at the right base, may give rise to right-sided abdominal pain and mimic appendicitis. Abdominal tenderness is minimal, pyrexia is marked and chest examination may reveal a pleural friction rub or altered breath sounds on auscultation. A chest radiograph is diagnostic.

Adults

Terminal ileitis

In its acute form terminal ileitis may be indistinguishable from acute appendicitis unless a doughy mass of inflamed ileum can be felt. An antecedent history of abdominal cramping, weight loss and diarrhoea suggests regional ileitis rather than appen­dicitis. The ileitis may be nonspecific, due to Crohn’s disease or Yersiniainfection. Yersinia enterocolitica causes inflammation of the terminal ileum, appendix and caecum with mesenteric adenopathy. If suspected, serum antibody titres are diagnostic and treatment with intravenous tetracycline antibiotic is appropriate. If Yersiniainfection is suspected at operation, a mesenteric lymph node should be excised, divided, and half submitted for microbiological culture (including tuberculosis) and half for histological examination.

Ureteric colic

Ureteric colic does not commonly cause diagnostic difficulty as the character and radiation of pain differ from those of appendicitis. Urinalysis should always be performed and the presence of red cells should prompt a supine abdominal X-ray. Renal ultrasound or an intravenous urogram is diagnostic.

Right-sided acute pyelonephritis

This is accompanied and often preceded by increased frequency of micturition. It may cause difficulty in diagnosis, especially in women. The leading features are tenderness confined to the loin, fever (temperature 390C), and possibly rigors and pyuria.

Perforated peptic ulcer

(Duodenal contents pass along the paracolic gutter to the right iliac fossa.) There is usually a history of dyspepsia and a very sudden onset of pain, which starts in the epigastrium and passes down the right paracolic gutter. In appendicitis the pain starts classically in the umbilical region. Rigidity and tenderness in the right iliac fossa are present in both conditions, but in perforated duodenal ulcer the rigidity is usually greater in the right hypochondrium. Radiography may show gas under the diaphragm. continuesunabated until operation. Usually there is a history of a missed menstrual period and urinary pregnancy test may be positive. Severe pain is felt when the cervix is moved on vaginal examination. Signs of intraperitoneal bleeding usual­ly become apparent and the patient should be questioned specifically regarding referred pain in the shoulder. Pelvic ultrasonography should be carried out in all cases where an ectopic pregnancy is a possible diagnosis.

Testicular torsion

Testicular torsion in a teenager or young adult male is easily missed. Pain can be referred to the right iliac fossa, and shyness on the part of patient may lead the unwary to suspect appendicitis unless the scrotum is examined in all cases.

Acute pancreatitis

Acute pancreatitis should be considered in the differential diagnosis of all adults suspected of acute appendicitis and when appropriate excluded by serum or urinary amylase measurement.

Rectus sheath haematoma

This is a relatively rare but easily missed differential diagnosis. It usually presents with acute pain and localised tenderness in the right iliac fossa, often after an episode of strenuous physical exercise. Localised pain without gastrointestinal upset is the rule. Occasionally, in an elderly patient, particularly those on anticoagulant therapy, a rectus sheath haematoma may present with a mass and tenderness in the right iliac fossa following minor trauma.

Adult females

It is in women of child-bearing age that pelvic disease most often mimics acute appendicitis. A careful gynaecological history should be taken in all women with suspected appen­dicitis concentrating on menstrual cycle, vaginal discharge and possible pregnancy. The most common diagnostic mim­ics are salpingitis, mittelschmerz, torsion or haemorrhage of an ovarian cyst and ectopic pregnancy.

Salpingitis

This is the condition which poses greatest diagnostic diffi­culty in young women. Typically, the pain is lower than in appendicitis and is bilateral. A history of vaginal discharge, dysmenorrhoea and burning pain on micturition are all help­ful differential diagnostic points. There may be a history of contact with sexually transmitted disease. When suspected, the opinion of a gynaecologist should be obtained, and high vaginal swab taken for Chlamydia culture. When serious diagnostic uncertainty persists, diagnostic laparoscopy should be undertaken.

Mittelschmerz

Midcycle rupture of a follicular cyst with bleeding produces lower abdominal and pelvic pain, typically midcycle. Sys­temic upset is rare, pregnancy test is negative and symptoms usually subside within hours. Occasionally, diagnostic laparo­scopy is required.

Torsion/haemorrhage of an ovarian cyst

This can prove a difficult differential diagnosis. When suspected, pelvic ultrasound and a gynaecological opinion should be sought. If encountered at operation, ovarian cystectomy should be performed, if necessary, in women of child-bearing years. Documented visualisation of the contralateral ovary is an essential medicolegal precaution.

Ectopic pregnancy

It is unlikely that a ruptured ectopic pregnancy, with its well-defined signs of haemoperitoneum, will be mistaken for acute appendicitis, but the same cannot be said for a right-sided tubal abortion, or still more for a right-sided unruptured tubal pregnancy. In the latter, the signs are very similar to those of acute appendicitis, except that the pain commences on the right side and stays there. The pain is severe and

Elderly

Sigmoid diverticulitis

In some patients with a long sigmoid loop, the colon lies to the right of the midline and it may be impossible to differentiate between diverticulitis and appendicitis. A trial of conservative management with intravenous fluids and antibiotics is often appropriate, with a low threshold for exploratory laparotomy in the face of deterioration or lack of clinical response.

Intestinal obstruction

The diagnosis of intestinal obstruction is usually clear, the subtlety lies in recognising acute appendicitis as the occa­sional cause in the elderly. As with diverticulitis, intravenous fluids, antibiotics and nasogastric decompression should be instigated with early resort to laparotomy.

Carcinoma of the caecum

When obstructed or locally perforated, carcinoma of the caecum may mimic or cause obstructive appendicitis in adults. A history of antecedent discomfort, altered bowel habit or unexplained anaemia should raise suspicion. A mass may be palpable (vide infra) and barium enema or colonoscopy is diagnostic.

Rare differential diagnoses

Preherpetic pain of the right 10th and 11th dorsal nerves is localised over the same area as that of appendicitis. It does not shift and is associated with marked hyperaesthesia. There is no intestinal upset or rigidity. The herpetic eruption may be delayed for 3—8 hours. Tabetic crises are now rare. Severe abdominal pain and vomiting usher in the crisis. Other signs of tabes confirm the diagnosis. Spinal conditions are sometimes associated with acute abdominal pain, especially in children and the elderly. These may include tuberculosis of the spine, metastatic carcinoma, osteoporotic vertebral collapse and multiple myeloma. The pain is due to compression of nerve roots and may be aggravated by movement. There is rigidity of the lumbar spine and intestinal symptoms are absent. The abdominal crises of porphyria and diabetes mellitus need to he remembered. A urinalysis should be tested in every abdominal emergency. In cyclical vomiting of infants or young children there is a history of previous similar attacks, and abdominal rigidity is absent. Acetone is found in the urine but is not diagnostic as it may accompany starvation. Typhlitisor leukaemic ileocaecal syndrome is a rare hut potentially fatal enterocolitis occurring in immunosuppressed patients. Gram-negative or clostridial(especially C. septicum) septicaemia can be rapidly progressive. Treatment is with appropriate antibiotics and haematopoetic factors. Surgical intervention is rarely indicated.

Investigation

The diagnosis of acute appendicitis is essentially clinical. A full blood count and urinalysis should be performed in all cases. In women of reproductive years, it is wise to obtain a urinary pregnancy test before proceeding to exploration. Pelvic ultrasound is of value in excluding tubal or ovarian disease if suspected. Abdominal ultrasound examination is a useful diagnostic tool, particularly in children, with a diagnostic accuracy of appendicitis in excess of 90 per cent

In dehydrated or elderly patients or where comorbid conditions dictate, serum urea and electrolytes should be checked. If a diagnosis of intestinal obstruction, intussusception or ureteric colic is being entertained, a supine abdominal X-ray should be performed .

Treatment

The treatment of acute appendicitis is appendicectomy. There is a perception that urgent operation is essential to prevent the increased morbidity and mortality of peritonitis. While there should be no unnecessary delay, all patients, particularly those most at risk of serious morbidity, benefit from a short period of intensive preoperative preparation. Intravenous fluids sufficient to establish adequate urine output (catheterisation is needed only in the very ill) and appropriate antibiotics should be given. There is ample evidence that a single perioperative dose of antibiotics reduces the incidence of postoperative wound infection. When peritonitis is suspected, therapeutic intravenous antibiotics to cover Gram-negative bacilli, as well as anaerobic cocci, should be given. Hyperpyrexia in children should be treated with salicylates in addition to antibiotics and intravenous fluids. With appropriate use of intravenous fluids and parentral antibiotics, a policy of deferring appendicectomy after midnight to first case on the following morning does not increase morbidity. However, when acute obstructive appendicitis is recognised, operation should not be deferred longer than it takes to optimise the patient’s condition.

Appendicectomy

Appendicectomy may be performed by conventional open operation or by using laparoscopic techniques. The first surgeon to perform deliberate appendicectomy for acute appendicitis was Lawson Tam, in May 1880. The patient recovered. It is recorded in 1736 that Claudius Amyand successfully removed an acutely inflamed appendix from the hernial sac of a boy.
Appendicectomy should he performed under general anaesthetic with the patient supine on the operating table. When a laparoscopic technique is to be used, a nasogastric tube should be inserted and the bladder must be empty (ensure the patient has voided before leaving the ward). Prior to preparing the entire abdomen with an appropriate antiseptic solution, the right iliac fossa should be palpated for a mass. If a mass is felt, it may, on occasion, be preferable to adopt a conservative approach (vide infra). Draping of the abdomen is in accordance with the planned operative technique, taking account of any requirement to extend the incision or convert a laparoscopic technique to open operation.

Conventional appendicectomy

When the preoperative diagnosis is considered reasonably certain, the incision that is widely used for appendicectomy is the so-called grid-iron incision (a grid-iron was a frame of cross-beams to support a ship during repairs). The grid-iron incision (described first by McArthur) is made at right angles to a line joining the anterior superior iliac spine to the umbilicus, its centre being along the line at McBurney’s point. In the subcutaneous tissues an arterial twig from the superficial circumflex iliac artery usually requires ligation. The external oblique is incised in the line of its fibres along the length of the incision. The fibres of the internal oblique and transversus abdominis are split, and with suitable retrac­tion the peritoneum is opened. If better access is required, it is possible to convert the grid-iron to a Rutherford Morrison incision (vide infra) by cutting the internal oblique and transversus muscles in the line of the incision.
In recent years, a transverse skin crease (Lanz) incision has become more popular, as the exposure is better and extension, when needed, is easier. The incision, appropriate in length to the size and obesity of the patient, is made approxi­mately 2 cm below the umbilicus centred on the midcla­vicular—midinguinal line. The external oblique aponeurosis, internal oblique and transversus muscles are split in the direction of the fibres and the peritoneum is opened. When necessary the incision may be extended medially, with retraction or suitable division of the rectus abdominis muscle.
When the diagnosis is in doubt, particularly in the presence of intestinal obstruction, a lower midline abdominal incision is to be preferred over a right lower paramedian incision. The latter, although widely practised in the past, is difficult to extend, more difficult to close and provides less good access to the pelvis and peritoneal cavity.
Rutherford Morrison’s incision is useful if the appendix
is paracaecal or retrocaecal and fixed. It is essentially an oblique muscle-cutting incision with its lower end over McBurney’s point and extending obliquely upwards and laterally as necessary. All layers are divided in the line of the incision.
Removal of the appendix
It will be assumed that the abdomen has been opened by a skin crease incision. A retractor is placed under the medial side of the wound and the peritoneum, and the abdominal wall is elevated. Serous exudate is removed with a sucker. Pus, if present, is likewise removed having first retained a specimen for microbiological culture. The caecum is identified by the presence of teniae coli, and using a finger or a swab the caecum is withdrawn. A turgid appendix may be felt at the base of the caecum. Inflammatory adhesions must be gently broken with a finger which is then hooked around the appendix to deliver it into the wound. The appendix is conveniently controlled using a Babcock or Lane’s forceps applied in such a way as to encircle the appendix and yet not damage it. The base of the mesoappendix is clamped in a haemostat, divided and ligated. When the mesoappendix is broad the procedure must be repeated with a second, or rarely, a third haemostat. The appendix, now completely freed, is crushed near its junction with the caecum in a haemostat, which is removed and reapplied just distal to the crushed portion. An absorbable 2/0 ligature is tied around the crushed portion close to the caecum. The appendix is amputated between the haemostat and the ligature. An absorbable 2/0 or 3/0 purse-string or ‘Z’ suture may then be inserted into the caecum about 1 cm from the base. The stitch should pass through the muscle coat, picking up the taeniae coli. The stump of the appendix is invaginated while the purse-string or ‘Z’ suture is tied, thus burying the appendix stump. Many surgeons believe that invagination of the appendiceal stump is unnecessary.

Methods to be adopted in special circumstances

When the caecal wall is oedematous, the purse-string suture is in danger of cutting out. If the oedema is of limited extent this can be overcome by inserting the purse-string suture into more healthy caecal wall at a greater distance from the base of the appendix. Occasions may arise when, because of the extensive oedema of the caecal wall, it is better not to attempt invagination.
When the base of the appendix is inflamed, it should not be crushed but ligated close to the caecal wall just tightly enough to occlude the lumen, after which the appendix is amputated and the stump invaginated. Should the base of the appendix be gangrenous, neither crushing nor ligation must be attempted. Two stitches are placed through the caecal wall close to the base of the gangrenous appendix, which is amputated flush with the caecal wall, after which these stitches are tied. Further closure is effected by means of a second layer of interrupted seromuscular sutures.

Retrograde appendicectomy

When the appendix is retrocaecal and adherent, it is an advantage to divide the base between haemostats. The appendiceal vessels are then ligated, the stump is ligated and invaginated, and gentle traction on the caecum will enable the surgeon to deliver the body of the appendix which is then removed from base to tip. Occasionally, this manoeuvre requires division of the lateral peritoneal attachments of the caecum.

Drainage of the peritoneal cavity

This is usually unnecessary provided adequate peritoneal toilet has been done. If, however, there is considerable purulent fluid in the retrocaecal space or the pelvis, a soft silastic drain may be inserted through a separate stab incision. The wound should be closed using absorbable sutures to oppose muscles and aponeurosis. In the presence of soiling or if a gangrenous appendix has been delivered through the wound, it is often wise to leave open or to delay primary closure by inserting a gauze wick between interrupted skin sutures (Brady).

Laparoscopic appendicectomy

The most valuable aspect of laparoscopy in the management of suspected appendicitis is as a diagnostic tool, particularly in women of child-bearing age. In general, an open technique should be used to establish a pneumoperitoneum, and for insertion of the laparoscopic ports as it is safer than the closed techniques using a Verres needle. The placement of the operating port may vary according to operator preference and previous abdominal scars. The operator stands to the patient’s left and faces a video monitor placed at the patient’s right foot. A moderate Trendelenberg tilt of the operating table assists delivery of loops of small bowel from the pelvis. The appendix is found in the conventional manner
by identification of the caecal taeniae and is controlled using laparoscopic tissue-holding forceps. By elevating the appen­dix the mesoappendix is displayed. A dissecting forceps is used to create a window in the mesoappendix to allow the appendicular vessels to be coagulated or ligated using a clip applicator. The appendix, free of its mesentery, can be ligated at its base with an absorbable loop ligature, divided and removed through one of the operating ports. It is not usual to invert the stump of the appendix. A single absorbable suture is used to close the linea alba at the umbilicus and the small skin incisions may be closed with a subcuticular suture.
Patients who undergo laparoscopic appendicectomy are likely to be discharged from hospital and return to work slightly sooner than those who have undergone open appendicectomy, but it remains to be seen whether this justifies the slightly longer operating time and higher costs involved.

Problems encountered during appendicectomy

• A normal appendix is found — this demands careful exclusion of other possible diagnoses, particularly terminal ileitis, Meckel’s diverticulitis and tubal or ovarian causes in women. It is usual to remove the appendix to avoid future diagnostic difficulties, even though the appendix is macroscopically normal, particularly if a skin crease or grid-iron incision has been made. A case can be made for preserving the macroscopically normal appendix seen at diagnostic laparoscopy, although approximately a quarter of seemingly normal appendices show microscopic evidence of inflammation.
• The appendix cannot be found — the caecum should he mobilised and the taenia coli should be traced to their confluence on the caecum before the diagnosis of ‘absent appendix’ is made.
• An appendicular tumour is found — small tumours (under 2.0 cm in diameter) can he removed by appendicectomy; larger tumours should he treated by a right hemicolectomy.
• An appendix abscess is found and the appendix cannot he removed easily — this should be treated by local peritoneal toilet, drainage of any abscess and intravenous antibiotics. Very rarely a caecectomy or partial right hemicolectomy is required. (The first recorded operation for an appendix abscess was by Henry Hancock of Charing Cross Hospital, London, in 1848.)
Appendicitis complicating Crohn’s disease
Occasionally, a patient is operated on for acute appendicitis who is found to have concomitant Crohn’s disease of the ileo-caecal region. Providing the caecal wall is healthy at the base of the appendix, appendicectomy can he performed without increasing the risk of an enterocutaneous fistula. Rarely, the appendix is involved with the Crohn’s disease. In this situation a conservative approach may be warranted, and a trial of intravenous corticosteroids and systemic antibiotics used to resolve the acute inflammatory process.

Appendix abscess

Failure of resolution of an appendix mass or continued spiking pyrexia usually indicates that there is pus within the phlegmonous appendix mass. Ultrasound or abdominal CT scan may identify an area suitable for insertion of a percutaneous drain. Should this prove unsuccessful, laparotomy through a midline incision is indicated.

Pelvic abscess

Pelvic abscess formation is an occasional complication of appendicitis and can occur irrespective of the position of the appendix within the peritoneal cavity. The most common presentation is a spiking pyrexia several days following appendicitis; indeed the patient may have already been discharged from hospital. Pelvic pressure or discomfort associated with loose stool or tenesmus is common. Rectal examination reveals a buggy mass in the pelvis, anterior to the rectum, at the level of the peritoneal reflection. Pelvic ultrasound or CT scan will confirm. Treatment is transrectal drainage under general anaesthetic.

Management of an appendix mass

If an appendix mass is present and the condition of the patient is satisfactory, the standard treatment is the conservative Ochsner—Sherren regimen. This strategy is based on the premise that the inflammatory process is already localised and that inadvertent surgery is difficult and may be dangerous. It may be impossible to find the appendix and, occasionally, a faecal fistula may form. For these reasons it is wise to observe a nonoperative programme, but to be prepared to operate should clinical deterioration occur.
Careful record of the patient’s condition and the extent of the mass should be made, and the abdomen regularly re­examined. It is helpful to mark the limits of mass on the abdominal wall using a skin pencil. A nasogastric tube should be passed and intravenous fluid and antibiotic therapy instigated. Temperature and pulse rate should be recorded 4-hourly and a fluid balance record maintained. Clinical deterioration or evidence of peritonitis is indication for early laparotomy. Clinical improvement is usually evident within 24—48 hours at which time the nasogastric tube can be removed and oral fluids introduced. Failure of the mass to resolve should raise suspicion of a carcinoma or Crohn’s disease. Using this regime approximately 90 per cent of cases resolve without incident. It is advisable to remove the appendix usually after an interval of 6—8 weeks.

Postoperative complications

Postoperative complications following appendicectomy are relatively uncommon and reflect the degree of peritonitis that was present at the time of operation and intercurrent diseases that may predispose to complications.
Wound infection
This is the most common postoperative complication which occurs in 5—10 per cent of all cases. This usually presents with pain and erythema of the wound on the fourth or fifth postoperative day, often soon after hospital discharge.Treatment is by wound drainage and antibiotics when required. The organisms responsible are usually a mixture of Gram-negative bacilli and anaerobic bacteria, predominantlyBacteroides species and anaerobic streptococci.

Intra-abdominal abscess

Intra-abdominal abscess has become a relatively rare complication after appendicectomy with the use of perioperative antibiotics. Postoperative spiking fever, malaise and anorexia, developing 5—7 days after operation, suggest an intraperi­toneal collection. Interloop, paracolic, pelvic and subphrenic sites should be considered. Abdominal ultrasonography and CT scanning greatly facilitate diagnosis and allow percuta­neous drainage. Laparotomy should be considered in patients suspected to have intrabdominal sepsis in whom imaging fails to show a collection, particularly those with continuing ileus.

Ileus

A period of adynamic ileus is to be expected after appen­dicectomy, and may last for a number of days following removal of a gangrenous appendix. Ileus persisting for more than 4—5 days, particularly in the presence of a fever, is indicative of continuing intra-abdominal sepsis and should prompt further investigation (see above).

Respiratory

In the absence of concurrent pulmonary disease, respiratory complications are rare following appendicectomy. Adequate postoperative analgesia and physiotherapy, when appropriate, reduce the incidence.

Venous thrombosis and embolism

These are rare after appendicectomy except in the elderly and women taking the oral contraceptive pill. Appropriate prophylactic measures should be taken in such cases.
Portal pyaemia (Pylephlebitis)
Pylephlebitis is a rare but very serious complication of gangrenous appendicitis associated with high fever, rigors and jaundice. It is due to septicaemia in the portal venous system and may leads to the development of intrahepatic abscesses (often multiple). Treatment is with systemic antibiotics and percutaneous drainage of hepatic abscesses as appropriate.

Faecal fistula

Leakage from the appendicular stump rarely occurs, but may follow if the encircling stitch has been put in too deeply or if the caecal wall was involved by oedema or inflammation. Occasionally, a fistula may result following appendicectomy in Crohn’s disease.

Adhesive intestinal obstruction

Adhesive intestinal obstruction is the most common late complication of appendicectomy. At operation often a single band adhesion is responsible. Occasionally, chronic pain in the right iliac fossa is attributed to adhesion formation after appendicectomy. In such cases laparoscopy is of value in confirming the presence of adhesions and allowing division.

Right inguinal hernia

This is said to be more common following a grid-iron incision for appendicitis due to injury to the iliohypogastric nerve.

Recurrent acute appendicitis

Appendicitis is notoriously recurrent. It is not uncommon for patients to attribute such attacks to ‘biliousness’ or dyspepsia. The attacks vary in intensity, may occur every few months and the majority of cases ultimately culminate in severe acute appendicitis. If a careful history is taken from patients with acute appendicitis many remember having had milder but similar attacks of pain. The appendix in these cases shows fibrosis indicative of previous inflammation. Chronic appendicitis, per se, does not exist. Patients labelled thus are usually examples of the recurrent form of the disease.

Less common pathological conditions

Mucocele of the appendix

Mucocele of the appendix may occur when the proximal end of the lumen slowly becomes completely occluded, usually by a fibrous stricture, and the pent up secretion remains sterile. The appendix is greatly enlarged and sometimes it contains several millilitres of mucus.The symptoms produced are those of mild subacute appendicitis unless infection supervenes, when the mucocele is converted into an empyema.Rupture of a mucocele of the appendix is a cause of pseudomyxoma peritonei. Occasionally, the mucocele is caused by a mucus secreting adenocarcinoma, in which case a right hemicolectomy is the correct treatment.

Diverticulae of the appendix

Diverticulosis of the appendix is relatively rare and the diverticulae may be true congenital (all coats) or acquired (no muscularis layer). The condition may occur in conjunction with mucocele, in which case the intramural pressure rises sufficiently to cause herniation of the mucous membrane through the muscle coat at several points. More often, there is no demonstrable obstruction to the lumen. The patient usually gives a history of previous recurrent attacks of appendicitis. If encountered during the course of an operation for another condition, a diverticulae­bearing appendix should be removed because of a propensity to perforate if inflamed.

Intussusception of the appendix

This is rare and occurs mostly in childhood. It can he diagnosed only at operation. The symptoms usually are not acute. Untreated, the condition may pass on to an appendiculocolic intussusception. The appendix may slough, and this accounts for most of the very rare cases in which the appendix is absent. The treatment is appendicectomy.

Neoplasms of the appendix

Carcinoid tumour (syn. argentaffinoma)

Carcinoid tumours arise in argentaffin tissue (Kulschitzsky cells of the crypts of Lieberkuhn) and are most commonly found in the vermiform appendix. Carcinoid tumour is found once in every 300—400 appendices subjected to histological examination and is 10 times more common than any other neoplasm of the appendix. In many instances the appendix had been removed because of symptoms of subacute or recurrent appendicitis. The tumour can occur in any part of the appendix, but it frequently does so in the distal third. The neoplasm feels moderately hard, and on sectioning the appendix it can be seen as a yellow tumour between the intact mucosa and the peritoneum. Microscopically, the tumour cells are small, arranged in small nests within the muscle and have a characteristic pattern using immunohistochemical stain for Chromogranin B. Unlike carcinoid tumours arising in other parts of the intestinal tract, carcinoid tumour of the appendix rarely gives rise to metastases. Appendicectomy has been shown to be sufficient treatment, unless the caecal wall is involved, the tumour is 2 cm or more in size, or involved lymph nodes are found, otherwise right hemicolectomy is indicated.

Primary adenocarcinoma

Primary adenocarcinoma of the appendix is extremely rare. It is usually of the colonic type and should be treated by right hemicolectomy (as a second-stage procedure if the condition is not recognised at the first operation).