Why Does This Pregnant Woman Have Rectal Bleeding?

A 30-year-old woman who is 9 weeks along in her third pregnancy presents to the hospital in Riyadh, Saudi Arabia, with sudden painless rectal bleeding. She explains that she has experienced this twice in the past 3 months, has had no recent constipation, hemorrhoids, or changes in bowel habits, has had no weight changes, and has not experienced any physical trauma or fever.

She notes that her two previous pregnancies were full-term, with no complications, and that she has no known medical conditions or previous surgeries.

She is admitted for further investigation.

Laboratory tests show all results to be within normal limits, including a complete blood count and coagulation profile.

Ultrasound is performed, which confirms fetal viability and gestational age. Further investigations are performed by a multidisciplinary, high-risk pregnancy team; results show no evidence of compromising fetal organogenesis.

After the team advises the patient of the risks and benefits of the radiological procedures, she declines scans with computed tomography (CT) and magnetic resonance imaging (MRI).

The patient undergoes sigmoidoscopy under conscious sedation, which reveals a small, fungating, intramural mass about 40 cm from the anal verge that bleeds readily to the touch; it measures 3 × 4 cm. The rest of the colon up to the terminal ilium appears normal.

Clinicians remove the mass during the sigmoidoscopy; the pathology report describes a tan, polypoid, and pedunculated mass measuring 2 × 1.1 × 1 cm. The stalk measures 0.5 × 0.5 cm. Sections show a tubulovillous adenoma with focal intramucosal carcinoma, stage TisNX; no stalk invasion is identified.

Surgeons excise the polyp completely, and tests show the resection margin is negative for dysplasia or carcinoma; thus, they consider the procedure as diagnostic and ultimately, therapeutic.

The patient remains under close observation and follow-up throughout her pregnancy. She has no further rectal bleeding. Throughout the rest of the pregnancy, she receives regular ultrasound examinations which show the fetus is growing normally and has no anomalies.

At 12 weeks 4 days gestation, clinicians perform an ultrasound for fetal nuchal translucency (NT) which shows normal measurements: crown rump length of 59 mm and NT of 1.0 mm. Likewise, second trimester anatomy scans at 21 weeks gestation confirm normal growth and fetal structure.

The patient decides not to undergo any further CT or MRI assessments during her pregnancy, despite being reassured that these scans are safe during the second and third trimesters.

The surgical team considers the histopathology of the completely excised polyp, and the complete resolution of the patient's symptoms as reassuring. They decide to postpone further imaging until after the delivery unless the patient develops further symptoms.

At 40 weeks' gestation, she goes into labor spontaneously and vaginally delivers a healthy baby girl with normal Apgar scores. The placenta is examined and found to be normal.

After an uneventful postpartum period and consultation with the colorectal surgical team, the patient is discharged. Two weeks after delivery, she presents to the outpatient clinic for a follow-up assessment with the surgical team, who advise her to have a colonoscopy in a year and then every 3 years thereafter.

Discussion

Clinicians reporting this case urge healthcare providers to have a high index of suspicion and to thoroughly investigate potentially non-obstetric causes of persistent and unusual symptoms during pregnancy, including malignancies.

The authors note that they believe this is the first reported case of detection of intramucosal colorectal cancer (CRC) in a polyp during a first-trimester pregnancy with a favorable outcome for both mother and fetus.

Rectal tumors in young patients are usually poorly differentiated and have a higher metastatic potential, resulting in a poor prognosis. While CRC occurs very rarely during pregnancy -- with an estimated incidence of just 0.002% -- it is a leading cause of death in women of childbearing age and is the seventh most common cancer in pregnant women (at a mean age of 31 years), even in the absence of a family history.

CRC during pregnancy, which is thought to be related to increased estrogen and progesterone receptors, is associated with both diagnostic and treatment challenges, the case authors note. Clinical symptoms such as constipation, abdominal pain, nausea, vomiting, anemia, and rectal bleeding may be misattributed to pregnancy, especially in the presence of hemorrhoids or anal fissures.

The limited options available for safe diagnostic testing may also interfere with timely diagnosis. In fact, the case authors noted, colon obstruction, perforation, and metastasis are more frequent in pregnant women with CRC than in non-pregnant women with the disease.

Determining the stage of the patient's cancer while limiting risk to the fetus requires use of optimal investigative methods and radiological techniques. While colonoscopy is relatively contraindicated during pregnancy, it remains the gold standard for arriving at a definitive diagnosis.

Potential adverse complications include placental abruption from the mechanical pressure applied to the uterus, fetal exposure to potential teratogenic medications, and fetal injury related to maternal hypoxia or hypotension during the procedure.

When rectosigmoid cancer is suspected, gentle flexible rectosigmoidoscopy is preferred, the case authors note. In addition, abdominal CT should be avoided during the first trimester due to the risk of radiation. Abdominal ultrasound and MRI may be used, but are less accurate than CT in detecting micrometastasis, and the relative safety of MRI is questionable due to the unknown potential risks associated with use of contrast agents during pregnancy.

Treatment choices are similarly restricted in pregnancy, due to fetal or maternal risks involved with surgery, which is the mainstay of treatment, radiation therapy, and chemotherapy (depending on the stage of the cancer). In some tragic cases, clinicians and the patient and family are forced to decide between saving the life of either the mother or the baby.

As shown in the medical literature, only 25 of 32 reported cases of CRC during pregnancy resulted in healthy live-born infants, the case authors note. The fetal deaths were due to a stillbirth, prematurity, or termination of pregnancy, not to the malignancy itself, even in cases of widespread metastatic disease.

The case authors also echo the prevailing opinion that the currently low incidence of CRC in pregnancy is likely to rise, as a result of the trend toward delayed childbirth, along with the increasing incidence of CRC in patients under age 40.

Regarding this case, the authors note that in contrast to other reported patients with CRC in pregnancy, this patient was young, with no family history of CRC, and her cancer was diagnosed very early in pregnancy. Most previously published cases involved advanced stages of CRC, diagnosed late and with a poor prognosis. Many of these cases necessitated patients undergoing abortion, chemotherapy, and surgical resections.

Clinical guidelines on the management of CRC in pregnancy state that if the diagnosis is made in the first 20 weeks of pregnancy, delaying treatment can lead to disease progression and endanger the mother's life. Thus, discontinuation of the pregnancy followed by the appropriate treatment modality based on the stage of the tumor is recommended.

Conclusion

The case authors conclude that for this young woman, early detection of the tumor prompted a complete resection during a sigmoidoscopy procedure, without endangering the gravid uterus, and they suggest that a screening program for pregnant or high-risk women planning a pregnancy would assist in early detection and management.

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