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Amniotomy Technique

  • Author: Nan G O'Connell, MD; Chief Editor: Christine Isaacs, MD  more...
 
Updated: Oct 26, 2014
 

Artificial Rupture of Amniotic Sac

Once amniotomy can be safely performed, the amniotic membrane perforator is advanced. If an amniotic hook is used, the handle of the device is held with one hand outside the vagina while 2 fingers of the opposite hand are placed in the vagina to guide the tip. Care should be taken to protect maternal tissues from the point. If an amniotic finger cot is used, the device is placed on the index or middle finger of the examining hand.

Once the hook reaches the amniotic sac, the tip is pushed up against the sac with the index or middle finger of the internal hand to pierce the membranes. The hook is then pulled through the membranes with the external hand holding the handle to create a hole in the sac. If an amniotic finger cot is being used, the pointed tip is dragged through the membranes with the finger to create the amniotomy.

The examining hand should remain in place to confirm that there has been no prolapse of the umbilical cord during the amniotomy.

The hand is then removed from the vagina The nature of the amniotic fluid (ie, clear, bloody, meconium-stained, or purulent) is documented, and the fetal heart rate should be monitored for several minutes after the procedure.

Approach to unengaged presenting part

If amniotomy is required but the presenting part is not well engaged, an assistant can apply external fundal or suprapubic pressure to keep the fetus in place while the amniotic fluid is slowly released. Before amniotomy, this pressure should be determined to be adequate to ensure that the fetal head is applied to the cervix.

When this technique is not feasible or has been attempted without success, a controlled amniotomy can be performed. In this instance, the patient should be taken to the cesarean suite and placed in the lithotomy position. A speculum is placed in the vagina, and the amniotic sac is visualized. A spinal needle is then used to make 1 or more small holes in the sac, thereby very slowly releasing amniotic fluid under direct visualization and allowing the presenting part to descend safely into the pelvis.

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Complications

The most common complication of amniotomy is cord prolapse, which usually occurs during the sudden and rapid egress of amniotic fluid. Rupture of a vasa previa during amniotomy can cause life-threatening fetal blood loss. Both of these complications require emergency cesarean delivery.

An increased incidence of chorioamnionitis is seen, especially with prolonged rupture of membranes. Cord compression associated with variable decelerations of the fetal heart rate occurs more often after amniotomy. Minor fetal scalp trauma may also occur, especially if the fetal head is closely applied to the membranes when amniotomy is performed.

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Contributor Information and Disclosures
Author

Nan G O'Connell, MD Assistant Professor, Department of Obstetrics and Gynecology, VCU Medical Center, Virginia Commonwealth University School of Medicine; Medical Director, Obstetrics and Gynecology Services, VCU Medical Center at Stony Point

Nan G O'Connell, MD is a member of the following medical societies: American College of Obstetricians and Gynecologists, Association of Professors of Gynecology and Obstetrics

Disclosure: Nothing to disclose.

Coauthor(s)

Breanna L Walker, MD Resident Physician, Department of Obstetrics and Gynecology, Virginia Commonwealth University Health System

Disclosure: Nothing to disclose.

Specialty Editor Board

John G Pierce, Jr, MD Associate Professor, Departments of Obstetrics/Gynecology and Internal Medicine, Medical College of Virginia at Virginia Commonwealth University

John G Pierce, Jr, MD is a member of the following medical societies: American College of Obstetricians and Gynecologists, Association of Professors of Gynecology and Obstetrics, Christian Medical and Dental Associations, Medical Society of Virginia, Society of Laparoendoscopic Surgeons

Disclosure: Nothing to disclose.

Chief Editor

Christine Isaacs, MD Associate Professor, Department of Obstetrics and Gynecology, Division Head, General Obstetrics and Gynecology, Medical Director of Midwifery Services, Virginia Commonwealth University School of Medicine

Christine Isaacs, MD is a member of the following medical societies: American College of Obstetricians and Gynecologists

Disclosure: Nothing to disclose.

References
  1. Cunningham, Levano, Bloom, Hauth, Rouse, Spong. Abnormalities of the Placenta, Umbilical Cord and Membranes. Williams Obstetrics. 23rd. United States: McGraw-Hill; 2010. Chapter 27.

  2. Nachum Z, Garmi G, Kadan Y, Zafran N, Shalev E, Salim R. Comparison between amniotomy, oxytocin or both for augmentation of labor in prolonged latent phase: a randomized controlled trial. Reprod Biol Endocrinol. 2010. 8:136. [Medline].

  3. Bricker L, Luckas M. Amniotomy alone for induction of labour. Cochrane Database Syst Rev. 2000. CD002862. [Medline].

  4. Cooley SM, Geary MP, O'Connell MP, McQuillan K, McParland P, Keane D. How effective is amniotomy as a means of induction of labour?. Ir J Med Sci. 2010 Sep. 179(3):381-3. [Medline].

  5. Cunningham, Lenevo, Bloom, Hauth, Rouse, Spong. Labor Induction. Williams Obstetrics. 23rd. United States: McGraw-Hill; 2010. Chapter 22.

  6. Howarth GR, Botha DJ. Amniotomy plus intravenous oxytocin for induction of labour. Cochrane Database Syst Rev. 2001. CD003250. [Medline].

  7. Selo-Ojeme DO, Pisal P, Lawal O, Rogers C, Shah A, Sinha S. A randomised controlled trial of amniotomy and immediate oxytocin infusion versus amniotomy and delayed oxytocin infusion for induction of labour at term. Arch Gynecol Obstet. 2009 Jun. 279(6):813-20. [Medline].

  8. Mitchell MD, Flint AP, Bibby J, Brunt J, Arnold JM, Anderson AB. Rapid increases in plasma prostaglandin concentrations after vaginal examination and amniotomy. Br Med J. 1977 Nov 5. 2(6096):1183-5. [Medline].

  9. Smyth RM, Alldred SK, Markham C. Amniotomy for shortening spontaneous labour. Cochrane Database Syst Rev. 2007. (4):CD006167. [Medline].

  10. Wei S, Wo BL, Xu H, Luo ZC, Roy C, Fraser WD. Early amniotomy and early oxytocin for prevention of, or therapy for, delay in first stage spontaneous labour compared with routine care. Cochrane Database Syst Rev. 2009 Apr 15. CD006794. [Medline].

 
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Amnicot
Amniotomy hook.
 
 
 
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