Suspected Pulmonary Embolism in Pregnancy

Abstract & Commentary

Synopsis: Ventilation/perfusion scanning appears to be safe and effective, at least in ruling out significant clinical pulmonary embolism in pregnant patients. However, prospective studies over longer time periods should be undertaken to validate these conclusions.

Source: Chan WS, et al. Suspected pulmonary embolism in pregnancy: Clinical presentation, results of lung scanning, and subsequent maternal and pediatric outcomes. Arch Intern Med. 2002;162:1170-1175.

Pulmonary embolism (PE) is a preventable cause of maternal mortality during pregnancy and the postpartum period. Once PE is suspected, many clinicians begin their evaluation with a ventilation/perfusion scan. Although scanning is assumed to be safe during pregnancy based on low fetal radiation exposure,1 no clinical data exist to support the notion that there are no adverse outcomes in pregnancy. In addition, little is known about ventilation/perfusion scan interpretation in pregnant women and the safety of withholding anticoagulation in those with normal or nondiagnostic scans.

The purpose of this multicenter, retrospective, observational study was to examine the distribution and safety of ventilation/perfusion scanning in pregnant patients. The safety of withholding anticoagulation therapy in pregnant women with normal or nondiagnostic scans was also examined.

A total of 120 consecutive pregnant patients who presented with suspected PE and had ventilation/perfusion scans were identified through the nuclear medicine departments. Patient demographics, stage of pregnancy, symptomatology, and treatment strategy at the time of original evaluation were recorded. Two independent experts re-interpreted the original ventilation/perfusion scans and categorized them as normal, nondiagnostic, or high probability. Patients were later contacted by telephone to determine postpartum venous thromoembolic events, and pregnancy outcomes.

Scan readings were as follows 87 (72.5%) normal, 29 (24.2%) nondiagnostic, and 4 (3.3%) high probability. Seven were receiving anticoagulation prior to presentation for previously diagnosed PE or deep venous thrombosis; eight women received anticoagulation subsequent to their evaluation. Of the 104 untreated women (1 died secondary to primary pulmonary hypertension), 80 had normal scans and 20 scans were nondiagnostic. In this group, no thromboembolic event was reported after a mean follow-up of 20 months.

Of 110 obstetrical and pediatric outcomes examined over 20 months, 3 spontaneous abortions, 4 congenital, and 4 developmental abnormalities were reported. No childhood cancers or leukemias were reported.

Comment by Alan Fein, MD, & Jonathan Edelson, MD

In this retrospectively examined group of pregnant patients, the prevalence of high probability scans is low (1.8%), compared to the other patients with suspected PE (10%). There were no thromboembolic events reported in those with normal or intermediate probability lung scans, suggesting that ventilation/perfusion scanning in pregant patients has a good negative pedictive value. Importantly, fetal risk was minimal in this population. The percentage of adverse fetal outcomes after ventilation/perfusion scanning was similar to that in the general population, 2.6% compared to 3.6%. These numbers are supported by previous studies that suggested no increase in fetal malformation risk for exposures less than 1 rad; radiation exposure in ventilation/perfusion scans is significantly lower.2

In summary ventilation/perfusion scanning appears to be safe and effective, at least in ruling out significant clinical PE in pregnant patients. However, prospective studies over longer time periods should be undertaken to validate these conclusions. 

References

1. Ginsberg JS, et al. Risks to the fetus of radiologic procedures used in the diagnosis of maternal thromboembolic disease. Thromb Haemost. 1989;61:189-196.

2. McCabe J, et al. Ventilation perfusion scintigraphy. Emerg Med Clin North Am. 1991;9(4):805-825.

Dr. Fein is Director and Dr. Edelson is Fellow, Division of Pulmonary and Critical Care Medicine, North Shore University Hospital, Manhasset, NY.

Special Feature: Total or Subtotal Hysterectomy: Which is Superior?

By Frank W. Ling, MD

As the "new kid on the OB/GYN Clinical Alert block," and as the generalist among the editors, I intend to focus on topics that come up commonly in my own practice of obstetrics and gynecology. The beauty of having this format is that cutting edge science can be presented, but also sacred cows can be challenged.

So our topic this time around is the most common major gynecologic surgical procedure in the United States, the hysterectomy. Stimulus for this discussion was provided in the New England Journal of Medicine in which Thakar and colleagues looked at the outcome of 279 benign cases randomized to either subtotal or total abdominal hysterectomy.1 Total hysterectomy was associated with longer operating time, more blood loss, longer hospitalization, more postoperative fever, and more frequent use of antibiotics. One-year follow-up revealed some complications more commonly associated with subtotal hysterectomy (cyclic vaginal bleeding, 6.8%; persistent pelvic pain, 2.3%; and cervical prolapse, 1.5%) and some with total hysterectomy (bowel obstruction, 1.4% and pelvic pain, 4.8%).

Of great interest to our patients are the following findings in both groups: 1) the incidence of bowel dysfunction did not increase over the preoperative state; 2) the incidence of lower urinary tract dysfunction decreased after surgery; 3) frequency of intercourse increased after surgery; 4) prevalence of deep dyspareunia declined after surgery; and 5) orgasms did not change from baseline.

These data should reinforce to each of us who performs hysterectomy the potential effect of how we counsel our patients regarding the surgical approach that we recommend. As gynecologic surgeons we are in a unique position to truly improve quality of life. Unlike other surgical specialties in which the doctor-patient relationship may well be limited to the procedure and the immediate postoperative period, ours is a lasting one. We will continue to see our surgical patients for both specific concerns as well as health care maintenance. It should be reassuring to both us and our patients that abdominal hysterectomy, either total or subtotal, does not appear to be associated with an increased incidence of problems related to gastrointestinal, urinary, or sexual functioning.

As an extension of these findings, each of us should also be reassessing what we recommend to our patients regarding which type of hysterectomy to have (total vs subtotal/supracervical) as well as what approach should be taken (abdominal vs vaginal vs laparoscopic-assisted vs laparoscopic). I raise these issues here because the data that can help us guide our patients must be based on sound evidence and not anecdotal information. Remember: not all publications are created equal. It is a good thing that our peer-reviewed literature provides an opportunity for a novel approach to be described or a series of satisfied patients to be reported. Neither of these examples, however, should necessarily change our pattern of care. Similarly, articles on "My favorite approach to . . ." or "How I perform . . ." in nonpeer-reviewed journals should not convince us or our patients to question established care. It is, however, a bad thing if choices of patient care on based upon inappropriate claims of superiority or inadequate data.

The discriminating consumer and the astute clinician cannot avoid being exposed to claims that supracervical hysterectomy is superior to total hysterectomy in terms of sexual functioning and organ prolapse. Is it true? It certainly has not been proven. By the same token, who has the experience to say that it isn’t? Answer: Nobody. There are no definitive data to support or refute the claim. Our job as both the surgeon and patient advocate should be to make sure that the patient truly is given informed consent about the risk and benefits of both, and that her concerns and preferences are fully addressed. One hint to keep perspective: If you feel as though you’re "selling" an operation, you probably are. Back up half a step and make sure that the informed consent is balanced and based on what we know. It remains a privilege to have women trust us as their surgeon and physician. These patients deserve the best that we can do, both in the operating room as well as in the office counseling session.

Reference

1. Thakar, R, et al. Outcomes after total versus subtotal abdominal hysterectomy. N Engl J Med. 2002;347: 1318-1325.