Cavernous hemangiomas of the sigmoid colon and rectum are uncommon vascular malformations usually found in young adults with a long history of episodic and painless rectal bleeding. Alternatively, they may present with massive life-threatening hemorrhage. Histologically, colonic hemangiomas are easily separated from telangiectasias and angiodysplasias. They are usually considered benign hamartomas arising from the submucosal vascular plexus and are attributed to embryonic sequestration of mesodermal tissue. However, large rectal cavernous hemangiomas can infiltrate the entire pelvis and behave aggressively. Colonic hemangiomas are divided into capillary and cavernous types. The former tend to be small and asymptomatic, whereas the cavernous type, which is more frequently encountered, is either discrete and circumscribed or diffuse and expansive (Gentry Classification). Large, tortuous vascular channels with turbulent, sluggish blood flow predispose to the formation of phleboliths. In fact, the clustering of such phleboliths in an unusual location in a young individual with rectal bleeding is very suggestive of a cavernous hemangioma of the colon or rectum, although phleboliths are absent in half of the cases or difficult to see. Interestingly, our patient had CT for other reasons 2 years before the current presentation and no calcifications were seen. One could speculate that the repeated stop-and-go bleeding during pregnancy together with the repeated activation of local hemostatic mechanisms led to the rapid formation of these calcifications. Several authors have pointed out that the diagnosis is often missed for decades even with repeated colonoscopic examinations, and patients frequently are subjected to hemorrhoidectomies that are of no benefit. The diagnosis was much more quickly established in our patient since one of us (PC) was familiar with the entity. CT is useful for evaluation of rectal hemangiomas, but if phleboliths are not present the diagnosis cannot be made with confidence or may be missed altogether. In our patient, the radiologist did not consider the possibility of cavernous hemangioma despite the presence of phleboliths. Characteristic MRI findings have been described and consist of rectal wall thickening with high signal intensity on T2-weighted images and abnormal perirectal fat with serpiginous structures. Phleboliths are difficult to see on MRI. Most patients with recurrent rectal bleeding from cavernous rectal hemangiomas are young and otherwise healthy, and few physicians proceed rapidly to pelvic CT or MRI and particularly not during pregnancy. The evaluation of rectal bleeding is straightforward in the overwhelming majority of cases. In nonpregnant patients with severe, recurrent bleeding, a contrast CT of the abdomen and pelvis scan is obtained as a first step after a nondiagnostic colonoscopy. Even if the cause is not immediately clear, CT findings may still narrow the selection of further imaging studies, such as angiography -- if a vascular fistula is suspected -- or MRI -- if a space-occupying lesion is found. If locally available, rectal endoscopic ultrasonography performed with a flexible Doppler-capable instrument, such as the GF-UE160, may be the diagnostic instrument of choice because it avoids radiation or magnetic field exposure and cost run-ups for lesions that appear inflammatory or neoplastic. No sedation is required, and a Doppler-flow evaluation with high-resolution imaging is possible. In addition, biopsies can be obtained with transrectal ultrasound-guided fine-needle aspiration if needed. Moreover, rectal ultrasonography is conducted by gastroenterologists or colorectal surgeons familiar with rare rectal pathology. In patients with diffuse cavernous rectal hemangioma who consider or elect surgery, MRI may give the most information for surgical planning, allowing an individualized surgical approach with the goal of anal sphincter preservation.[1,7]
Many primary care physicians are not familiar with this rare entity, and it is worth pointing out that not all bright-red blood per rectum is related to benign hemorrhoids. In pregnancy, endorectal ultrasonography may be the imaging modality of choice in perplexing cases.
Medscape J Med. 2008;10(9):206 © 2008
Cite this: Massive Hemorrhage in Pregnancy Caused by a Diffuse Cavernous Hemangioma of the Rectum -- EUS as Imaging Modality of Choice - Medscape - Sep 03, 2008.