Unusual Endoscopic and Microscopic View of Enterobius Vermicularis: A Case Report With a Review of the Literature

Posted 10/20/2005

Michelle Petro, MD; Kalyana Iavu, MD; Anil Minocha, MD
Author Information

Abstract

Enterobius vermicularis has the broadest geographic range of any helminth and is the most common intestinal parasite seen in the primary care setting. Underappreciated is the fact that it is not always a benign disorder and could even cause life-threatening medical problems. Visualization of the actual worms during endoscopy is probably underappreciated in part because endoscopists have never actually seen the worm and/or are not actively looking for, or anticipating, worms. This report describes a case of worm infection as documented during colonoscopy and confirmed by microscopy. The gross and microscopic appearance of the worm is described. Literature regarding the wide range of gastrointestinal and nongastrointestinal manifestations, including potentially life-threatening illnesses, as well as treatment options, are also reviewed.

Introduction

Enterobius vermicularis is a nematode and has the broadest geographic range of any helminth.^[1] Since the first evidence of pinworm infection from Roman-occupied (30 BC to AD 395) Egypt,^[2] it has been known to be the most common intestinal parasite seen in the primary care setting, regardless of race, socioeconomic status, or culture.^[3] Although infection with this worm is usually thought to be asymptomatic or to cause nuisance symptoms such as perianal itching, this worm can cause severe and even life-threatening illnesses,^[4-26] including fatality in primates.^[27] Visualization of the actual worms during endoscopy is unusual and probably underappreciated, in part because most endoscopists have never seen these worms in real life and are not consciously looking for worms. We present a case of a worm infection as documented during colonoscopy and confirmed by microscopy.

Case Report

The patient was a 30-year-old female without a significant medical history who presented with complaints of crampy, lower abdominal pain and bloating on a daily basis. She also complained of diarrhea described as approximately 2 to 3 loose stools per day for about 1 to 2 days per month. The pain was not affected by any modifying factors including food intake, bowel movements, or increased anxiety or stress. She reported no weight loss, dysphagia, nausea, vomiting, gastrointestinal bleeding, jaundice, or constipation. Her surgical history was significant for a cesarian section. She reported no smoking, alcohol consumption, or illicit drugs. Her family history was significant for colon cancer in her grandfather and great aunt.

Physical examination revealed a fairly well-built and well-nourished female in no acute distress. She was afebrile with normal vital signs. Her abdominal examination revealed a well-healed surgical incision in her lower abdomen. Bowel sounds were normal in all four quadrants. There was mild tenderness to palpation in her bilateral lower quadrants, but no organomegaly or any masses were appreciated. The laboratory data, including complete blood count, basic chemistry profile, and coagulation studies, were within normal limits.

She underwent a colonoscopy for her symptoms of abdominal pain and intermittent diarrhea, in addition to her family history of colon cancer. There was an approximately 4-mm pinworm seen moving in the rectosigmoid area (Fig. 1). The worm was removed with biopsy forceps. Colorectal mucosa throughout was normal, both endoscopically and histologically. Histopathology of the worm confirmed it to be an E. vermicularis female with multiple eggs (Fig. 2).