ANSWER 60
The clinical picture suggests obstruction to outflow from the stomach. This would be com-
patible with vomiting of residual food some time after eating and the succussion splash from
the retained fluid and food in the stomach. The biochemical results fit with this diagnosis.
There is a rise in urea but not creatinine, suggesting a degree of dehydration. Sodium, chlor-
ide and hydrogen ions are lost in the vomited stomach contents. Loss of hydrochloric acid
produces a metabolic alkalosis. In compensation, hydrogen ions are retained by exchange
for potassium in the kidney and across the cell membranes, so leading to hypokalaemia, and
carbonic acid dissociates to hydrogen ions and bicarbonate. The hypokalaemia indicates
a considerable loss of total body potassium, which is mostly in the skeletal muscle, and
explains the patient’s recent weakness.
The most likely cause would be a carcinoma of the stomach involving the pyloric antrum
and producing obstruction to outflow. A chronic gastric ulcer in this area could produce
the same picture from associated scarring, and gastroscopy and biopsy would be neces-
sary to be sure of the diagnosis.
Gastroscopy may be difficult because of retained food in the stomach. In this case, after
this was washed out a tumour was visible at the pylorus causing almost complete obstruc-
tion of the outflow tract of the stomach. The next step would be a computed tomography
(CT) scan of the abdomen to look for metastases in the liver and any suggestion of local
spread of the tumour outside the stomach. If there is no evidence of extension or spread,
or even to relieve obstruction, laparotomy and resection should be considered. Otherwise
chemotherapy and surgical palliation are treatment options.
- Vomiting food eaten a long time previously suggests gastric outlet obstruction.
- Mild-to-moderate dehydration tends to increase urea more than creatinine.
- Prolonged vomiting causes a typical picture of hypochloraemic metabolic alkalosis.
- Carcinoma of the stomach can present without abdominal pain or anaemia.