BACKGROUND: Most women in the United States will have a routine sonogram during pregnancy. The medical necessity of this is debatable. The goal of our study was to examine maternal beliefs about prenatal sonography.

METHODS: We surveyed 150 prenatal patients at their point of entry to maternity care at a large military medical center. The main outcome measures were the patient’s desire for a prenatal sonogram, the reasons for wanting a sonogram, the number of sonograms wanted, and the patient’s willingness to pay for the examination.

RESULTS: Of the 150 eligible subjects, 137 (91%) participated and 135 (98%) wanted a prenatal sonogram. Fifty-one (37%) of the respondents were willing to pay for the sonogram if it was not ordered by their provider. The reasons for wanting a sonogram (to determine the sex of the fetus, to ensure that the fetus was healthy, general maternal reassurance, and to ensure adequate fetal growth) were similar across age, race, and income (military rank).

CONCLUSIONS: Our study indicates that most women want a sonogram during pregnancy, and many are willing to pay for the examination. Women appear to want sonograms for reasons that may not assist their provider with immediate clinical decision making. This is a potentially important disagreement between cost-saving and patient satisfaction that maternity care providers must consider when deciding whether to perform prenatal sonography for women with low-risk pregnancies.

Between 60% and 70% of pregnant women in the United States will have a sonogram at some point during pregnancy,¹ at a cost of more than $1 billion to the health care system. The utility of routine antenatal sonograms is debatable. Some sources feel that screening sonography is cost-effective during pregnancy,^2,3 and argue for its routine use.⁴ Others suggest that it increases the cost of prenatal care,⁵ does not improve perinatal outcome,^6,7 and offers little benefit in low-risk patients.⁸ The United States Preventive Services Task Force has recommended against routine third-trimester sonography and states that there is insufficient evidence to recommend for or against routine second-trimester sonography in otherwise low-risk patients.⁹

Much of the discussion about screening sonography for women with low-risk pregnancies, however, has focused on medical measures or birth outcomes. Less is known about how women feel about sonography within the context of their pregnancies. It has been reported that if appropriate positive feedback is given to the patient during the examination, a sonogram is generally reassuring to her.^10,11 With the increased availability of ultrasound technology, many women now expect and some “positively demand” sonography during pregnancy.¹² Prenatal sonography could represent an important area of conflict between patient autonomy and the clinical decision-making process.¹³

Our study was designed to address several questions pertaining to maternal perceptions of prenatal sonography: (1) What percentage of women wants to have a sonogram as part of prenatal management? (2) Why do women want prenatal sonography? (3) How many sonograms do women want during a pregnancy? (4) Are women willing to pay for the sonograms if they are not offered as part of routine prenatal care?

Methods

Sample Recruitment

We conducted our study at the Naval Medical Center San Diego, a large tertiary referral center with 300 to 400 deliveries per month. All subjects were eligible for care in the military health care delivery system, a program that provides free care without deductibles or copayments to eligible patients. Following institutional approval, 150 consecutive low-risk prenatal patients were asked to participate at their point of entry to the maternity care system. Exclusion criteria included first trimester vaginal bleeding, suspected ectopic pregnancy, uncertain clinical dates, history of previous congenital anomaly, late entry to prenatal care, intrauterine device in place at time of conception, infertility patients, maternal medical complications, advanced maternal age, and suspected uterine abnormality.

Survey Administration

A 12-item survey was administered to participating patients that included questions about their age, race, number of previous pregnancies, and number of living children. Patients were then asked whether they wanted a sonogram during the current pregnancy, and if yes, how many. They were given the opportunity to describe the reasons for wanting (or not wanting) a pre-natal sonogram. Patients were also asked whether they would be willing to pay for a sonogram if their clinician did not order one during the pregnancy and how much they would pay.

Data Analysis

Descriptive statistics were used for categorical variables. Nonparametric statistical analyses (chi-square analysis, Fisher exact test) were used to determine differences between groups and to calculate correlation coefficients (Pearson’s and Spearman-rho).

Results

Of the 150 women recruited for participation, 137 (91%) completed the survey. Of those, 135 (98%) stated that they wanted a sonogram during their pregnancy. The other 2 women were unsure. None of the respondents indicated that they did not want prenatal sonography. Subjects ranged in age from 14 to 34 years. Patient ethnicity and sponsor’s rank (a surrogate marker for family income) are presented in [Table 1].

The reasons most commonly cited for wanting a sonogram were: (1) to determine the sex of the fetus, (2) to ensure that the baby was healthy, (3) for general reassurance, and (4) to rule-out specific fetal abnormalities ([Table 2]). Other reasons included “seeing the baby,” and determining the due date, the number of fetuses, and the size and position of the baby.

Fifty-one (37%) of the respondents stated that they were willing to go elsewhere to pay for a sonogram if one was not ordered by their clinician. They were willing to pay an average of $85 per sonogram.

The number of sonograms patients wanted varied widely. The median number of sonograms desired was 2 per pregnancy. The reasons women listed for wanting prenatal sonograms, their willingness to pay, and the number of sonograms wanted did not vary according to age, race, rank, or previous pregnancy.

Discussion

The value of diagnostic testing is typically discussed in the context of clinical decision making. That is, how does a diagnostic test help a physician to rule in or rule out disease? Diagnostic tests are also described as being cost-effective or cost-ineffective relative to what information they provide versus the resources they require. Berwick and Weinstein¹⁴ propose an interesting decision-making model that divides information provided by diagnostic testing into what is useful to the physician and what is useful to the patient. Using this model to describe prenatal ultrasound, 44% of the value of the examination was outside of the realm of medical decision making. In that study from the Boston area in 1985, prenatal patients were willing to pay an average of more than $700 per sonogram to obtain this information. That is much more than the women in our study were willing to pay. This discrepancy is most likely attributable to socioeconomic variances in the populations studied and the different reimbursement climates sampled.

Prenatal sonography is unique among diagnostic tests, because many patients appear to enjoy the examination, many expect it, and some even demand it.^12,13 Given its increasing availability, screening prenatal sonography runs the risk of becoming the de facto standard of care without supportive clinical evidence.¹⁵ Our results reinforce the popular demand of prenatal sonography.

Our study also suggests that many of the reasons women cite for wanting a prenatal sonogram (eg, wanting to know the sex of the baby, general maternal reassurance, and so forth) are outside the realm of traditional medical decision making. The information that the patient seeks may not help the physician clinically manage the pregnancy; patients often want different information than their physicians need. In an age of increasing patient autonomy, physicians should carefully balance patient desires and expectations against the clinical usefulness of the information provided by prenatal sonography.

In our study, more than one third of the patients wanted a prenatal sonogram for reasons generally associated with maternal reassurance. This is an important point for physicians to consider when counseling patients. The probability of delivering a child without major birth defects in low-risk prenatal patients is 97% to 98%.^16-18 Data from the Routine Antenatal Diagnostic Imaging Ultrasound Study indicate that the sensitivity of prenatal sonography for detecting a fetus with a major anomaly before delivery is 35%.⁸ Extrapolating this to low-risk pregnancies, the reassurance provided by a normal sonogram increases the likelihood of a normal outcome (defined as delivering a fetus without a major birth defect) by less than 1%. Thus, it is possible that patients might overestimate the value of sonography for purposes of maternal reassurance in low-risk pregnancies.

In our study of pregnant patients who are accustomed to free health care, more than half were willing to pay for a sonogram during their pregnancy. To achieve this patients were willing to leave the boundaries of the traditional physician-patient relationship to obtain the examination. Those patients wanting a sonogram whose clinicians did not order one would have to find a third party willing to perform the examination and would have to pay the full cost of the sonogram. This represents a potentially significant conflict between physician integrity (not wanting to order an unindicated test) and patient autonomy (wanting to have a prenatal sonogram).¹⁹

Although prenatal sonography unquestionably plays a central role in the management of complicated pregnancies, its role in routine low-risk pregnancies remains controversial. In routine pregnancies, popular demand may not coincide with scientific utility. Some women will want multiple sonograms when that is not clinically indicated, and some women may assume that sonography is a routine part of prenatal care. Physicians must carefully consider whether to obtain a prenatal sonogram within the context of each pregnancy. In arriving at the decision of whether to perform prenatal sonography for each patient, care must be taken to preserve the patient right to autonomy while respecting the intellectual and scientific integrity of the physician.

Acknowledgments

This project was supported by BUMED protocol S-98-058.

The Maternal Perspective on Prenatal Ultrasound