M O Ahn

University of Southern California, Los Angeles, CA, United States

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Publications (18)42.45 Total impact

  • M O Ahn, K Y Cha, J P Phelan
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    ABSTRACT: In the management of the preterm pregnancy, cesarean delivery cannot be supported in the delivery of the preterm (less than 1500 g) cephalic-presenting fetus. Although cesarean may be of benefit in the management of the preterm breech fetus (less than 1500 g), there is yet no perspective randomized clinical trial to support its use.
    Clinics in Perinatology 07/1992; 19(2):411-23. · 2.58 Impact Factor
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    S A Jun, M O Ahn, Y D Lee, K Y Cha
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    ABSTRACT: Early fetal growth delay and early oligohydramnios have been suspected as signs of embryonal jeopardy. However, little information is available for the prediction of early abortion. Sonographic examination of 111 early pregnancies between the sixth and ninth gestational week with regular, 28 day menstrual cycles was performed to investigate predictable sonographic findings of early abortion. Sonographic measurements of the gestational sac (G-SAC), crown-rump length (CRL) and fetal heart rate (FHR) were performed using a linear array real time transducer with Doppler. All measurements of 17 early abortions were compared to those of 94 normal pregnancies to investigate the objective rules for the screening of early abortion. Most of the early aborted pregnancies were classified correctly by discriminant analysis with G-SAC and CRL (G-SAC = 0.5222 CRL + 14.6673 = 0.5 CRL + 15, sensitivity 76.5% specificity 96.8%). With the addition of FHR, 94.1% of early abortions could be predicted. In conclusion, sonographic findings of early intrauterine growth retardation, early oligohydromnios and bradycardia can be predictable signs for the poor prognosis of early pregnancies.
    Journal of Korean Medical Science 04/1992; 7(1):34-9. · 1.25 Impact Factor
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    ABSTRACT: A case is presented of an amnionic rupture sequence which led to massive fetal ventral herniation and lordoscoliosis. Characteristic ultrasonographic findings of an omphalocele, fetal attachment to the placenta, and the absence of free-floating umbilical cord were observed.
    Journal of Korean Medical Science 07/1991; 6(2):177-81. · 1.25 Impact Factor
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    ABSTRACT: Electronic fetal heart rate and uterine activity monitoring during labor requires expensive equipment and a source of electricity. However, it is not available to most of the women in the world. Intrauterine manometry provides a method which can be employed in underdeveloped settings to assess uterine contractions and to time auscultation. The vertical column of fluid in a standard intrauterine pressure catheter (IUPC) correlated well (R = 0.93) with the intrauterine pressure measurements obtained by a standard IUPC/pressure transducer system. Intrauterine manometry provides an alternative measure of uterine tone which may be employed in underdeveloped areas.
    International Journal of Gynecology & Obstetrics 05/1991; 34(4):315-8. · 1.84 Impact Factor
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    ABSTRACT: Of 2081 high-risk pregnancy patients who underwent antepartum fetal surveillance tests, 72 (3.5%) patients demonstrated evidence of polyhydramnios using the amniotic fluid index to assess the amniotic fluid volume. In these patients, an increased incidence of fetal macrosomia, premature births, non-reactive nonstress tests, perinatal morbidity, and fetal anomalies was observed. These data suggest that if polyhydramnios is encountered during an ultrasound evaluation, consideration should be given to the possibility of latent or uncontrolled diabetes mellitus or fetal macrosomia or anomaly; fetal surveillance and genetic evaluation also should be considered.
    Journal of Perinatology 01/1991; 10(4):347-50. · 2.25 Impact Factor
  • J Y Cho, M O Ahn, K S Cha
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    ABSTRACT: Recently, we developed the "window operation" as a more effective way to treat Bartholin gland cysts and abscesses. The window operation was used to treat 25 Bartholin cysts and 22 Bartholin abscesses during a 3-year period from October 1, 1986 to September 30, 1989. Under local anesthesia, a small piece of skin including the cyst wall was excised in an oval shape, and suturing was performed along the excised margin. Postoperative antibiotics were given in cases of acute inflammation. A new mucocutaneous junction was observed at the 4-week postoperative checkup. No complications or recurrences have been observed during the study period. The window operation can be an alternative method of treatment for Bartholin gland cysts or abscesses.
    Obstetrics and Gynecology 12/1990; 76(5 Pt 1):886-8. · 4.80 Impact Factor
  • A P Sarno, M O Ahn, J P Phelan
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    ABSTRACT: The amniotic fluid index (AFI), a semiquantitative technique for assessing amniotic fluid volume, has been shown to be a useful adjunct in antepartum surveillance. We evaluated the usefulness of the AFI in the early intrapartum period as it relates to subsequent fetal morbidity and fetal heart rate patterns. Two hundred term gravidas presenting in the latent phase of labor with vertex-presenting fetuses were studied. An intrapartum AFI less than or equal to 5.0 cm was associated with a significant increase in the risk of cesarean section for fetal distress and of an Apgar score of less than 7 at one minute as well as abnormal fetal heart rate patterns in late labor. The majority (71.4%) of the patients with an intrapartum AFI less than or equal to 5.0 cm had ruptured membranes on entry; however, there was no significant difference in outcome when they were compared to patients with intact membranes and oligohydramnios. Variable decelerations on entry were associated with oligohydramnios in 43.8% of the patients. An AFI less than or equal to 5.0 cm in the early intrapartum period is a risk factor for perinatal morbidity and abnormal fetal heart rate patterns in subsequent labor, and ruptured membranes in early labor are a risk factor for oligohydramnios.
    The Journal of reproductive medicine 08/1990; 35(7):719-23. · 0.75 Impact Factor
  • A P Sarno, J P Phelan, M O Ahn
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    ABSTRACT: This study evaluated subsequent fetal heart rate (FHR) patterns and fetal outcome in laboring women with normal or abnormal initial FHR patterns. Four hundred term gravidas presenting in the latent phase of labor were studied. Ninety (22.5%) exhibited abnormalities on the initial tracing, with the majority of those abnormalities (58.9%) including mild variable decelerations, either alone or in combination with other abnormalities. An analysis of the outcome for those patients revealed a significant increase in cesarean delivery for fetal distress and depressed one-minute Apgar scores when compared to patients with initially normal tracings. Analysis of subsequent FHR patterns in that group showed a significant increase in the incidence of atypical variable declerations and bradycardia. Patients with more than one abnormality on the initial FHR tracing showed a greater incidence of loss of variability, loss of reactivity and bradycardia on subsequent FHR tracings. Likewise, pregnancy outcome for this group was remarkable for an increased risk of meconium staining, cesarean delivery for fetal distress and depressed one-minute Apgar scores. An abnormal initial FHR tracing seems to be associated with the subsequent development of ominous FHR patterns and increased fetal morbidity, particularly when more than one abnormality is present on the initial tracing.
    The Journal of reproductive medicine 04/1990; 35(3):239-42. · 0.75 Impact Factor
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    ABSTRACT: Fetal acoustic stimulation has recently received much attention in the literature. This study evaluates fetal acoustic stimulation in the early intrapartum period as a predictor of subsequent fetal condition. The study group consisted of 201 patients, approximately 60% of whom had complicated pregnancies. All were in the latent phase of labor with singleton, vertex-presenting fetuses. Gestational age ranged from 37 to 43 weeks. Fourteen of the 201 fetuses (7%) showed a nonreactive response to fetal acoustic stimulation and those fetuses were at significantly greater risk of initial and subsequent abnormal fetal heart rate patterns, meconium staining, and cesarean delivery because of fetal distress and Apgar scores less than 7 at both 1 and 5 minutes. Transient fetal heart rate decelerations after a reactive response occurred in 25% of patients; however, fetal outcome was not worse in this group. A reactive response to fetal acoustic stimulation was associated with high specificity and negative predictive values. Therefore we conclude that fetal acoustic stimulation in the early intraprtum period may discriminate the compromised from the noncompromised fetus.
    American Journal of Obstetrics and Gynecology 04/1990; 162(3):762-7. · 3.88 Impact Factor
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    ABSTRACT: This study examines the usefulness of umbilical artery Doppler velocimetry, amniotic fluid volume assessment, and fetal heart rate data in the early intrapartum period as predictors of subsequent fetal distress. A total of 109 patients seen in the latent phase of labor in the labor and delivery area were studied. Both an abnormal initial fetal heart rate and an amniotic fluid index less than or equal to 5.0 cm were associated with a significant increase in the incidence of intrapartum fetal distress. Conversely, a systolic/diastolic ratio greater than 3.0 by Doppler ultrasonography was not associated with increased fetal morbidity. Overall, the sensitivities, specificities, and positive predictive values of the fetal heart rate tracing and the amniotic fluid volume assessment were comparable. Doppler systolic/diastolic ratios showed very poor sensitivity and positive predictive value. We conclude that the fetal heart rate tracing or the assessment of amniotic fluid volume in the early intrapartum period are reasonable predictors of subsequent fetal condition. The lack of patients with the absence of or reverse umbilical velocity preclude conclusions with regard to Doppler systolic/diastolic ratios for this purpose.
    American Journal of Obstetrics and Gynecology 01/1990; 161(6 Pt 1):1508-14. · 3.88 Impact Factor
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    ABSTRACT: Vaginal birth after cesarean delivery in a woman with breech presentation is a controversial issue. In this prospective study, 137 patients had a breech presentation. Of them, 27 (19.7%) met the protocol criteria for attempted vaginal delivery and desired a trial of labor. Thirteen (48%) achieved vaginal delivery, with no increase in fetal or maternal morbidity. Our data suggest that in selected patients, a trial of labor after a cesarean delivery with a breech presentation is a reasonable consideration.
    The Journal of reproductive medicine 11/1989; 34(10):831-3. · 0.75 Impact Factor
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    ABSTRACT: The pregnancy outcomes of 56 women with a twin gestation and a prior cesarean birth were analyzed to determine whether a trial of labor was a reasonable consideration. Of these patients, 31 (55%) underwent an elective repeat cesarean delivery and 25 (45%) attempted vaginal delivery. Of those who attempted vaginal delivery, 18 (72%) were vaginally delivered of both infants. The dehiscence rate among women with twin pregnancies who attempted a trial of labor was 4% compared with 2% in women with singleton pregnancies. There were no significant differences in maternal or neonatal morbidity or mortality rates in trial of labor versus no trial of labor groups. We conclude in this limited population that a trial of labor in a twin gestation after a previous cesarean delivery appears to be a reasonable consideration. The usual safeguards for attempted vaginal delivery in the twin gestation should be followed.
    American Journal of Obstetrics and Gynecology 08/1989; 161(1):29-32. · 3.88 Impact Factor
  • M O Ahn, J P Phelan
    Clinical Obstetrics and Gynecology 07/1989; 32(2):228-34. · 1.84 Impact Factor
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    ABSTRACT: The cesarean delivery rate has quadrupled during the past two decades, resulting in considerable attention focused on alternatives to cesarean birth. One option, vaginal birth after one previous cesarean, has come to be recognized as an acceptable alternative to routine elective repeat cesarean delivery. The purpose of this report was to evaluate whether women with two previous cesareans can safely undergo a trial of labor. Between July 1, 1982 and June 30, 1986, data were collected prospectively on all women with previous cesareans. Those with a known classical incision or a medical or obstetric contraindication to a trial of labor were excluded from an attempted vaginal delivery. During this period, 67,784 patients were delivered, of whom 6250 (9.2%) had had a previous cesarean. Of the 6250 previous-cesarean patients, 1088 (17.4%) had had two previous cesareans; of these, 501 (46%) underwent a trial of labor and 346 (69%) delivered vaginally. Whereas the overall rate of uterine dehiscence was 3%, the rate in those women who attempted a vaginal delivery was 1.8%, versus 4.6% in those who did not. Overall, oxytocin was used in 284 (57%) and was associated with a dehiscence rate of 2.1%, versus 1.4% in the no-oxytocin group. Successful vaginal delivery was related significantly to the use of oxytocin and to a previous vaginal delivery. Trial of labor in patients with two previous cesareans appears to be a reasonable consideration.
    Obstetrics and Gynecology 03/1989; 73(2):161-5. · 4.80 Impact Factor
  • M O Ahn, J P Phelan
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    ABSTRACT: The critical aspects of twin pregnancy begin with early diagnosis. After that, diet, bed rest, and frequent visits to the physician's office will enhance fetal outcome. Additionally, frequent ultrasound evaluations to assess fetal growth and fetal surveillance are also invaluable adjuncts. Prompt treatment of any medical or obstetrical complications will contribute to an overall improvement in maternal and fetal outcome.
    Clinics in Perinatology 04/1988; 15(1):55-69. · 2.58 Impact Factor
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    ABSTRACT: Whenever a patient has the subjective perception of decreased fetal movement, prompt evaluation in the form of antepartum fetal surveillance has been undertaken. The purpose of this report is to describe our experience with 489 pregnant women who came between Jan. 1 and Dec. 31, 1985 to our Antepartum Fetal Surveillance Clinic with this complaint alone or in association with another indication for fetal surveillance. Overall, 838 nonstress tests were performed, and the results were reactive, 93.2%; nonreactive, 6.8%; and fetal heart rate decelerations, 6.1%. Comparison of the first nonstress test results between those with decreased fetal movement alone or in combination with another diagnosis demonstrated a similar incidence of nonreactivity and fetal heart rate decelerations. In those patients whose indication was decreased fetal movement alone, there was a 3.7 times greater likelihood of diminished amniotic fluid volume. When the last test within 7 days of delivery was analyzed, the decreased fetal movement alone group had a lower incidence of cesarean delivery, cesarean delivery for fetal distress, and Apgar scores less than 7 than patients with an additional indication for testing. In summary, decreased fetal movement continues to be an acceptable indication for fetal surveillance. Based on our retrospective experience, the most reasonable approach appears to be a combination of nonstress test and amniotic fluid volume assessment. Unless the patient has additional indications for fetal surveillance, the patient with decreased fetal movement with a reactive nonstress test and a normal amniotic fluid volume does not appear to warrant additional testing.
    American Journal of Obstetrics and Gynecology 11/1987; 157(4 Pt 1):860-4. · 3.88 Impact Factor
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    ABSTRACT: Amniotic fluid volume assessment has become an important part of antepartum fetal surveillance. The amniotic fluid index (AFI), or four-quadrant technique, has been suggested for this purpose. While previous reports have outlined this technique and correlated the results with pregnancy outcome, none have reviewed the changes in AFI throughout pregnancy. We studied AFI changes from 11 through 43 weeks' gestation. As part of the entry criteria, only patients with good dates were evaluated. The AFI was determined by the summation of the vertical diameter of the largest pocket in each of the four quadrants. All amniotic fluid studies were conducted using real-time linear array B-scan. During the study period, 197 patients with good dates confirmed clinically and sonographically underwent 262 AFI assessments. From 11 to 26 weeks the AFI rose progressively. Thereafter until term, the AFI remained approximately 16.2 +/- 5.3 cm. After 38 weeks the AFI appeared to gradually decline. Data obtained from this study population corroborate previously defined normal amniotic fluid volumes. These results also suggest that serial measurements of the AFI may be an effective means of assessing fetal status throughout pregnancy.
    The Journal of reproductive medicine 09/1987; 32(8):601-4. · 0.75 Impact Factor
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    ABSTRACT: While the use of the four-quadrant technique, or the amniotic fluid index (AFI), for amniotic fluid volume assessment has been shown to correlate with perinatal outcome, one concern among clinicians is the reliability of a single AFI measurement. The purpose of this investigation was to ascertain the margin of error using this technique among 23 term and postterm women. The AFI was obtained using linear array real-time B-scan ultrasound to measure the vertical diameter of the largest amniotic fluid pocket in each of the four quadrants. The sum of these measurements was expressed as the AFI. Eight women underwent ten consecutive AFI measurements by the same sonographer to determine intraobserver variation. Interobserver variation between five sonographers was measured by assessing the AFI in 15 additional patients. With the amniotic fluid volume in the low or normal range, our results demonstrated the intraobserver and interobserver variations in AFI to average 1.0 and 2.0 cm, respectively. With an above-normal amniotic fluid volume, a 2.5- to 3-fold greater variation was observed. A relatively small margin of error appears to exist between observers using the four-quadrant technique to assess amniotic fluid volume.
    The Journal of reproductive medicine 09/1987; 32(8):587-9. · 0.75 Impact Factor