Pancreatic pseudocyst

A large watery pancreatic exudate sometimes collects in a patient's lesser sac. This has no epithelial lining, hence the term ''pseudo'cyst.

He usually presents some weeks after an abdominal injury, or an attack of acute pancreatitis, with a mass in his abdomen and epigastric discomfort or pain. He may be toxic with fever and tachycardia, but he is not nearly as ill as he would be if he had acute pancreatitis, or a pancreatic abscess. The mass usually distends his abdomen: it may extend right across his epigastrium, and reach down to his umbilicus or beyond it. It is tender, tense, immobile, and is often not fluctuant. Sometimes, he has symptoms of pancreatic insufficiency, with steatorrhoea.

If you make an opening between the cyst and his stomach, it will drain, without, surprisingly, the food in his stomach causing problems inside the cyst. You will have to open the anterior wall of his stomach, and then make another opening through its posterior wall into the cyst (cystogastrostomy). The correct timing of this is important (see below). Draining it is less urgent than operating on a pancreatic abscess (5.10b), and there is less chance of complications.

Fig. 13-6 A PANCREATIC PSEUDOCYST. A, the approach to the cyst through the anterior and posterior walls of the stomach. B, the wall of the cyst sutured to the posterior wall of the stomach to control bleeding. After Cattell and Warren in Maingot R, ''Abdominal Operations', (4th edn 1961) p. 557 Fig. 26. HK Lewis, permission requested.

PANCREATIC PSEUDOCYST SPECIAL TESTS. The patient's serum amylase is usually raised. If he is jaundiced (unusual), liver function tests will show the changes of obstructive jaundice.

IMAGING. Ultrasound is much better than X-rays. If you are using X-rays: (1) Give him some barium. A lateral film of his stomach will show a mass bulging into the barium shadow from behind. A barium meal shows gross widening of the normal contour of his duodenum. You may see patches of calcification in his pancreas. Or, (2) insert a nasogastric tube. Inject 200 ml of air into his stomach and take a lateral supine view of his abdomen. In a pancreatic pseudocyst the stomach is displaced forwards, in an amoebic liver abscess, backwards.

THE DIFFERENTIAL DIAGNOSIS includes an amoebic abscess (31.12), hepatoma (32.26), an infected hydatid cyst (31.13), a hydronephrosis, pyloric stenosis (11.6), Burkitt's lymphoma (32.3), abdominal tuberculosis (29.5), gastric carcinoma (32.25), and an aortic aneurysm.

CYSTOGASTROSTOMY [s7]FOR A PANCREATIC PSEUDOCYST WHEN TO OPERATE. Don't operate until 6 weeks after an attack of pancreatitis, by which time the cyst wall will be mature enough to take sutures. Once a pancreatic pseudocyst is palpable it rarely disappears spontaneously. Operate as soon as possible after 6 weeks; if you leave it too long it may bleed, rupture, become infected, or destroy much of his pancreas.

However, if after an attack of pancreatitis the cyst is enlarging rapidly, and rupture is imminent (rare), drain the cyst to the exterior with a large Malecot catheter[md]even before 6 weeks have elapsed. Don't try to do an anastomosis. Some surgeons consider external drainage disastrous.

RESUSCITATION. If he is dehydrated, wasted, or toxic, prepare him suitably. He may need parenteral fluids for a few days. Insert a nasogastric tube the previous evening, and wash out his stomach thoroughly.

INCISION. Make a median or paramedian incision (9.2).

Choose an area on the anterior wall of his stomach that is overlying the cyst. Use a knife to start a 6 cm incision in the long axis of his stomach between 2 Babcock forceps. Enlarge it with scissors. Clamp any briskly bleeding vessels, and retract the edges of the incision, so that you can inspect the posterior wall of his stomach. Suck it empty.

After opening his stomach, cautiously insert a needle connected to a syringe through its posterior wall into the mass (this is your last chance if you find it is an aortic aneurysm!). Expect to find a mildly opaque straw-coloured, or murky brownish fluid. If so, insert a small haemostat through the hole in his stomach into the cyst, and open it so as to enlarge the opening. Then insert forceps to enlarge the opening gently a bit more to 5 cm. Suck out the fluid, expect to aspirate up to 4 litres.

CAUTION ! Don't incise the cyst, it may bleed severely.

Lift up the cyst wall on sponge forceps and enlarge the incision until it is 6 cm long. There is no need to suture the stomach wall to the cyst, because they are already tightly stuck together. You will need to control brisk bleeding, so quickly oversew the opening all round with a continuous interlocking haemostatic stitch of 2/0 silk. Lock it (G, 4-7) because if one bite goes the whole must not collapse. Use silk, because pancreatic juice digests catgut. Reinforce the continuous suture with four interrupted 1/0 silk sutures at the ends and the middle of the elliptical incision.

When you are sure the posterior opening in the stomach is no longer bleeding, close the anterior one in two layers, the first a full-thickness haemostatic continuous layer of 3/0 chromic catgut sutures, and the second one a seromuscular Lembert layer of continuous catgut, silk, or cotton. Close his abdominal wall in the usual way.

POSTOPERATIVELY, ''suck and drip' him for 4 to 5 days (9.9, A 15.5), until his suture lines are well-healed, and he has bowel sounds. Then start a fluid diet. Postoperative complications are unusual.