Thromboembolism prophylaxis and cesarean section: a survey of general obstetricians. (Original Article).

Background: Venous thromboembolism (VTE) has historically remained a risk factor for obstetric patients, particularly those requiring cesarean section. The objective of this survey was to assess the response of general obstetricians to risk factor considerations for VTE prophylaxis and cesarean section.

Methods: A survey regarding VTE prophylaxis and cesarean section was sent to 113 obstetricians practicing in suburban Chicago and northern Wisconsin.

Results: There were 51 responses (45%) to the survey. Most respondents do not routinely use VTE prophylaxis for cesarean section in patients who may have one or more risk factors.

Conclusion: There appears to be lack of consensus or appreciation for VTE and prophylaxis for cesarean section. Further studies and education are warranted.

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Pregnancy is a risk factor for venous thromboembolism (VTE); the incidence is up to 5 times higher for pregnant women than nonpregnant women. (1) VTE during pregnancy is the leading cause of morbidity and mortality, reported to occur in 0.05% to 0.3% of pregnancies. (2) Bonnar (3) found Cesarean delivery to have a 10-fold higher incidence of fatal pulmonary embolism when compared with vaginal delivery. Two studies note the incidence of VTE after cesarean section to be 2.5 to 20 times that of vaginal delivery. (4,5) Despite these published factors, there remains no clear consensus in regard to VTE prophylaxis in obstetric patients, particularly those requiring cesarean section. The purpose of this survey was to assess the types of VTE prophylaxis used by obstetricians in the presence of selected clinical risk factors.

Methods

Between June and October 2001, 113 surveys were sent to the members of obstetrics and gynecology departments at St. Francis Hospital and Evanston Northwestern Healthcare in Evanston, Illinois, and Marshfield Clinic, a multispecialty clinic located in multiple sites in northern and central Wisconsin. The surveys were returned anonymously via departmental mail and requested a response regarding the method of VTE prophylaxis for cesarean section based on the presence of various clinical risk factors requiring prophylaxis as noted by Shaw et a1 (6) (Table 1). Results were tabulated as to the method of prophylaxis for each risk factor (Table 2). Responses describing combination methods (subcutaneous heparin plus elastic compression stockings and/or sequential compression devices) were considered as one method of prophylaxis.

Results

A total of 51 responses (45%) were received. Thirty-two respondents (64%) currently do not use any method of prophylaxis with the risk factors presented, with the exception of a family history or history of thromboembolism. Combination methods were the most common methods of prophylaxis, with the use of subcutaneous heparin or low molecular weight heparin alone less common. This lack of consensus is similar to that found in a survey of maternal-fetal medicine specialists in regard to the indications and use of peripartum VTE prophylaxis. (7,8)

Discussion

We believe this is the first survey of general obstetricians regarding the method of VTE prophylaxis and cesarean section. The elements of Virchow's triad for the pathogenesis of VTE (venous stasis, increase in coagulation factors, and tissue trauma) obviously are factors present at cesarean section.9 In a recent survey of the incidence of VTE during pregnancy, Ghenman et al (1) found that most pulmonary embolisms that occurred in the postpartum period were strongly associated with cesarean section. Additional studies have described similar concerns. (3,10) Postpartum VTE has been shown to be 3 to 5 times as frequent as antepartum events and 3 to 16 times more common after cesarean delivery. (11,12)

A number of risk factor prediction assessments have been proposed as guides for appropriate forms of VTE prophylaxis. (13) Most recommendations from consensus panels regarding prophylaxis have been based on trials with nonpregnant patients. (14) Simpson et al, (14) in a review of a perinatal database to determine risk .factors for pregnancy-related VTE, noted twice as many events postpartum as antepartum. Cesarean section, body mass index greater than 25, and maternal age greater than 35 were all factors increasing the incidence of thrombosis. (14) Prophylaxis scoring systems for surgical patients have been also proposed, (15) and according to this classification mechanism, all patients having cesarean section should be treated with sequential compression devices or antiembolism stockings. In regard to cost-benefit evaluation, the cost of various modalities for VTE prophylaxis used at the participant hospitals is shown in Table 3. The first randomized controlled trial as a pilot protocol for the use of low mo lecular weight heparin in preventing VTE after cesarean section was recently published. (16) The incidence of postoperative thrombosis was 1.3%, and the study showed feasibility in terms of follow-up and compliance.

Conclusions

Venous thromboembolism among obstetric patients remains a concern, and recent publications regarding the risk of VTE after cesarean section suggest that prophylaxis should be offered more frequently than obstetricians may be providing when selected risk factors are present. The use of antiemholism stockings or sequential compression devices should be considered as a minimum standard practice, if heparin is contraindicated. An initial pilot study has shown low molecular weight heparin to be of benefit, (16) and additional randomized controlled trials are necessary. Although this was a small survey sample, the lack of consensus and appreciation of risk factors underscores the increased need for education and study in preventing a potentially fatal complication in patients historically and physiologically at high risk for the development of VTE.

Table 1

Risk factors for venous thromboembolism and cesarean section indicating
the need for prophylaxis (6)


Age over 35 years
Weight ovcr 180 lb
Parity >3
Severe varicose veins
Infection
Emergency cesarcan section
Pregnancy-induced hypertension
Cesarean section requiring hysterectomy
History (or fami]y history) of VTE

Table 2

Survey respondents' (n = 51) choices for prophylaxis against venous
thromboembolism (a)

Risk factor                         None  ECS  SCD  SQ heparin  LMWH

Age over 35                          42    4    1       1        0
Weight over 180                      39    4    5       1        0
Parity > 3                           45    5    1       0        0
Severe varicose veins                32    2    1       0        0
Infection                            42    1    2       0        0
Emergency cesarean section           36    3    6       0        0
Pregnancy-induced hypertension       44    1    3       0        0
Requiring hysterectomy               22    t   19       0        0
History (or family history) of VTE    0    1    1       28       2

Risk factor                         Combination

Age over 35                              3
Weight over 180                          2
Parity > 3                               0
Severe varicose veins                   16
Infection                                6
Emergency cesarean section               6
Pregnancy-induced hypertension           3
Requiring hysterectomy                   9
History (or family history) of VTE      19

(a)ECS, elastic comprehension stockings; SCD, sequential comprehension
device; SQ heparin, subcutaneous heparin; LMWH, low molecular weight
heparin

Table 3

Average cost of VTE prophylaxis (3 days of therapy)


Elastic compression stockings        $40.00
Sequential compression device (SCD)  $149.00
Subcutaneous heparin                 $0.69/dose (2-3 times per day)
Low molecular weight heparin         $11.47/dose (1-2 times per
                                      day)

Accepted May 24, 2002.

References

(1.) Gherman RB, Goodwin TM, Leung B, Byrne JD, Hethumumi R, Montoro M. Incidence, clinical characteristics, and timing of objectively diagnosed venous thromboembolism during pregnancy. Obstet Gynecol 1999;94:730-734.

(2.) Rutherford S, Montoro M, McGhee W, Strong T. Thromboembolic disease associated with pregnancy: An 11 year review. Am J Obstet Gynecol 1991;164:286 (abstr).

(3.) Bonnar J. Can more be done in obstetric and gynecologic practice to reduce morbidity and mortality associated with venous thromboembolism? Am J Obstet Gvnecol 1999;180:784-791.

(4.) Greer IA. Epidemiology, risk factors and prophylaxis of venous thromboembolism in obstetrics and gynaecology. Baillieres Clin Obstet Gynaecol 1997;11:403-430.

(5.) Treffers PE, Huidekoper BL, Weenink GH, Kloosterman GJ. Epidemiological observations of thrombo-embolic disease during pregnancy and in the puerperium, in 56,022 women. Int J Gynaecol Obstet 1983;21:327-331.

(6.) RCOG Working Party. Report of the RCOG Working Party: Prophylaxis against Thromboembolism in Gynaecology and Obstetrics. London, Royal College of Obstetricians and Gynaecologists, 1995.

(7.) Evans W, Laifer SA, McNanley TJ, Ruzycky A. Management of thromboembolic disease associated with pregnancy. J Matern Fetal Med 1997;6:21-27.

(8.) Onyeife CI, Sherer DM, Bernstein PS, et al: Peripartum thromboembolism prophylaxis: A survey of practiced methods among perinatologists. J Soc Gynecol Investig 1999;6(Suppl): 177A (abstr).

(9.) Greer IA: Thrombosis in pregnancy: Maternal and fetal issues. Lancet 1999;353:1258-1265.

(10.) Rutherford SE, Phelan JP. Deep venous thrombosis and pulmonary embolism in pregnancy. Obstet Gynecol Clin North Am 1991;18:345-370.

(11.) Aaro LA, Juergens JL. Thrombophlebitis associated with pregnancy. Am J Obstet Gynecol 1971;109:1128-1136.

(12.) Kierkegaard A. Incidence and diagnosis of deep vein thrombosis associated with pregnancy. Acta Obstet Gynecol Scand 1983;62:239-243.

(13.) Weiss N, Bernstein PS. Risk factor scoring for predicting venous thromboembolism in obstetric patients. Ant. J Obstet Gynecol 2000;182:1073-1075.

(14.) Simpson EL, Lawrenson RA, Nightingale AL, Farmer RD. Venous thromboembolism in pregnancy and the puerperium: Incidence and additional risk factors from a London perinatal database. BJOG 2001;108:56-60.

(15.) Caprini JA, Arcelus JI, Hasty JH, Tamhane AC, Fabrega F. Clinical assessment of venous thromboembolic risk in surgical patients. Semin Thromb Hemost 1991;17(Suppl 3):304-312.

(16.) Burrows RF, Gan ET, Gallus AS, Wallace EM, Burrows EA. A randomised double-blind placebo controlled trial of low molecular weight heparin as prophylaxis in preventing venous thrombolic events after caesarean section: A pilot study. BJOG 2001;108:835-839.

RELATED ARTICLE: Key Points

* Venous thromboembolism (VTE) risk is greater after cesarean section than after vaginal delivery.

* On the basis of the results found with VTE scoring systems, as well as the results of studies of pregnancyrelated VTE, most patients who undergo cesarean section should be administered some form of prophylaxis.

* Currently, there is a lack of consensus or appreciation of VTE risk and appropriate prophylaxis for cesarean section.

From the Department of Obstetrics and Gynecology, Marshfield Clinic, Wausau, WI.

Address reprint requests to Thomas Connolly, DO, Marshfield Clinic, Department of Obstetrics and Gynecology, 2727 Plaza Drive, Wausau, WI 54401.

Copyright [c] 2003 by The Southern Medical Association 0038-4348103/9602-0146