Parasite life cycle and migration
Human infection occurs by ingesting eggs that have previously matured in the soil. Once in the stomach and then the small intestine, the larvae do not remain in place, but embark on a complex migration through the body:
- Penetrate the intestinal mucosa into the bloodstream (portal venous system).
- Reach the liver, from where they enter the lungs via the lesser circulation.
- Exit the vessels into the lumen of the respiratory tract: bronchioles, then bronchi, and ascend to the pharynx.
- Swallowed again along with sputum.
- Pass through the stomach once more and settle in the intestine, where they mature into adults.
It is this migration and the large size of the adult worms that cause the majority of surgical pathologies.
Intestinal and appendiceal complications
Intestinal obstruction Most commonly occurs in children and adolescents against the background of a massive infestation. A huge bolus of ascarids physically blocks the intestinal lumen, causing obturation obstruction.
- Symptoms: Patients complain of cramping abdominal pain, abdominal distension, delayed stool and gas passage. In later stages, vomiting of intestinal contents develops.
- Diagnostics: Palpation of the abdomen may reveal a painful, dough-like mass (the worm bolus itself), which can disappear and reappear. Abdominal X-ray reveals Kloiber's sign (fluid levels).
- Treatment: Begins with conservative management. If ineffective, laparotomy is indicated. The surgeon does not resect the bowel, but carefully massages the bolus and pushes the helminths into the large intestine. Postoperative medical deworming is mandatory.
Acute appendicitis Develops if an ascarid crawls into the lumen of the vermiform appendix. The clinical presentation is indistinguishable from standard appendicitis, and the presence of the parasite is usually an incidental finding during surgery.
Hepatobiliary and pancreatic involvement
Less commonly, helminths migrate from the intestinal lumen through the major duodenal papilla into the ductal systems of the digestive glands.
Bile ducts and liver The penetration of individual worms or entire clusters into the common bile duct, intrahepatic ducts, or gallbladder causes acute, rapidly progressive conditions with severe intoxication. Potential consequences:
- Obstructive jaundice;
- Purulent cholangitis;
- Acute cholecystitis;
- Liver abscesses.
Ultrasound, CT, or retrograde cholangiography are used for diagnosis. Treatment is strictly surgical: cholecystectomy, opening of the common bile duct to extract ascarids, external duct drainage, as well as opening and draining liver abscesses.
Pancreas If the parasite enters the pancreatic duct, it leads to pancreatitis. This can present as acute inflammation (including severe hemorrhagic variants) or as a chronic indurative process. In such cases, pancreatotomy is performed to extract the helminth, followed by antihelminthic therapy.
Organ perforation and surgical risks
A healthy organ wall will not perforate on its own; however, if there are pathological changes in the esophagus, stomach, or intestines (ulcerative defects, mucosal necrosis), ascarids can cause perforation. This inevitably leads to purulent peritonitis.
Specific postoperative complications Any surgical intervention stimulates helminth hyperactivity, prompting them to migrate actively. This is extremely hazardous:
- If ascarids are expelled with vomit, they can enter the respiratory tract and cause mechanical asphyxia.
- During surgeries involving the opening of hollow organ lumens, parasites can crawl through surgical suture lines directly into the free peritoneal cavity, provoking severe purulent peritonitis.
Important rule: Due to these fatal risks, all patients scheduled for elective surgery must undergo stool testing for helminth eggs. If positive, the surgery is postponed until complete preoperative deworming is achieved.
Briefly: answers to topical questions
What anthelmintic medications are used for mandatory medical deworming after resolving an intestinal obstruction?
Pyrantel is used for medical deworming. The main stages of treatment for obturation obstruction:
- Surgical stage — laparotomy, massaging the ascarid bolus, and pushing it into the large intestine.
- Conservative stage — mandatory subsequent deworming with anthelmintic drugs, among which pyrantel is the drug of choice.
What changes in the complete blood count are characteristic of the acute migratory stage of ascariasis?
During the migratory stage of ascariasis, a complete blood count may reveal eosinophilia, which can indicate systemic sensitization. The migratory stage is caused by toxic-allergic phenomena. A differential blood count is recommended for all patients with suspected ascariasis.
What are the indications for bowel resection in acute intestinal obstruction caused by an ascarid bolus?
In the provided sources, an indication for bowel resection specifically for intestinal obstruction caused by an ascarid bolus is not stated. If conservative therapy fails, laparotomy, massaging the ascarid bolus, and advancing it into the large intestine, followed by deworming, is recommended. Intestinal necrosis is listed as an indication for small bowel resection in acute intestinal obstruction in general, without specific reference to ascariasis.
Larval organ route: "I-L-L-P-I" — Intestine, Liver, Lungs, Pharynx, Intestine. The larva makes a loop through the lungs to become an adult in the intestine.
Class and exam questions
Can intestinal obstruction due to ascariasis be detected on plain radiographs?
Yes, fluid levels within the intestinal loops, known as Kloiber's cups, will be visible on the radiograph.
Why doesn't the surgeon resect part of the bowel during obstruction caused by an ascarid bolus?
In most cases, bowel viability is preserved. It is sufficient for the surgeon to gently massage the bolus with their fingers and push the parasites into the large intestine.
What is the main condition for intestinal perforation by an ascarid?
For perforation to occur, the GI tract wall must already be compromised (e.g., presence of an ulcer or mucosal necrosis).
Why test stool for helminth eggs before elective hernia repair?
Surgical stress forces helminths to migrate actively. They may emerge with vomit and cause asphyxia, or crawl through intestinal suture lines, causing peritonitis.
What else to study on this topic
- Conservative management of obturation intestinal obstruction
- Retrograde cholangiography in the diagnosis of parasitic biliary tract lesions
- Management tactics for purulent cholangitis and liver abscesses
- Preoperative and postoperative deworming: drugs and regimens
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