Errors Associated with Oxytocin Use: A Multi-Organization Analysis by ISMP and ISMP Canada

PROBLEM: Intravenous (IV) oxytocin used antepartum is indicated to induce labor in patients with a medical indication, to stimulate or reinforce labor in selected cases of uterine inertia, and as an adjunct in the management of incomplete or inevitable abortion. Used postpartum, IV oxytocin is indicated to produce uterine contractions during expulsion of the placenta and to control postpartum bleeding or hemorrhage. However, improper administration of oxytocin can cause hyperstimulation of the uterus, which in turn can result in fetal distress, the need for an emergency cesarean section, or uterine rupture. Sadly, a few maternal, fetal, and neonatal deaths have been reported.

In October 2019, ISMP Canada published a multi-incident analysis¹ to identify opportunities to improve the safe use of this high-alert medication. A total of 144 reports of incidents associated with oxytocin were analyzed from voluntary reports submitted to ISMP Canada and the Canadian National System for Incident Reporting (NSIR) between 2000 and 2019. Maternal, fetal, or neonatal harm was reported in 12% of the oxytocin reports to ISMP Canada and 29% of the oxytocin reports to NSIR. Most of the incidents reported in both data sets occurred during drug administration. 

In February 2020, ISMP analyzed an additional 52 voluntary reports associated with oxytocin submitted to the ISMP National Medication Errors Reporting Program (ISMP MERP) between 1999 and 2019. About 10% of the reports described more than one oxytocin error that had occurred. About 44% of the reported events originated during dispensing, with many relating to mix-ups between oxytocin and look-alike product vials. About a quarter (23%) originated during administration, and 13% during prescribing. Overall, about 8% of the reports were hazards that did not result in errors. A quarter (25%) of all events resulted in maternal, fetal, or neonatal harm.

Analysis of the 144 incidents reported to ISMP Canada and NSIR revealed 3 main themes, some with multiple subthemes. Analysis of the 52 reports submitted to ISMP revealed similar themes along with a few additional themes. The five themes from both ISMP Canada and ISMP analysis of oxytocin incidents are presented below.

THEME 1:  PRESCRIBING ERRORS

Selection of wrong drug on order entry screen. Oxytocin errors related to prescribing were associated with selecting the wrong drug from a computerized prescriber order entry (CPOE) screen when searching using only 3 letters, “PIT,” “OXY,” or “OXY10.” Most recently, two errors were reported in which physicians had entered “PIT” for PITOCIN (oxytocin) in the CPOE system but accidentally selected PITRESSIN (discontinued brand name for vasopressin still found in some CPOE systems). When entering “OXY10” into the CPOE system, the following error occurred:

A physician intended to prescribe oral OXYCONTIN (oxyCODONE) 10 mg every 12 hours as needed for pain for a postpartum patient. He entered “OXY10” into the CPOE search field but accidentally selected “oxytocin 10 units IV” from the menu, resulting in an order for oxytocin 10 units IV every 12 hours as needed for pain. The pharmacist was concerned about the order but dispensed the medication as prescribed because the nurse was waiting for the medication. The nurse also questioned the pharmacist about the order, stating that she had never given a patient “IV oxytocin” to treat pain. But by the time the pharmacist followed up with the prescriber and corrected the error, the patient had received one dose of IV oxytocin. 

THEME 2:  LOOK-ALIKE DRUG PACKAGING AND NAMES

Look-alike vials. Not unexpected, 40% of all oxytocin-related reports submitted to ISMP described look-alike vials that had led to, or could have led to, mix-ups between oxytocin and another product. The most common, recent reports involved both generic (oxytocin) and brand (Pitocin) vials (10 units/mL) that looked similar to ondansetron vials (4 mg/2 mL) from various manufacturers. The oxytocin/Pitocin and ondansetron vials are available in similar sized, clear vials with green caps (and sometimes green lettering on both labels). The risk of a mix-up between these products is heightened because they are often stored alphabetically near each other on pharmacy shelves and used for the same patient population, especially during cesarean sections. In some cases, a shortage of ondansetron was a factor requiring purchase of an available product from a different manufacturer in vials that looked similar to oxytocin/Pitocin vials. Many of the reported errors involved dispensing or stocking automated dispensing cabinets (ADCs) with the wrong product. Reports of other medications packaged in vials that look similar to oxytocin/Pitocin within the past 5 years included clindamycin and metoclopramide.

Look-alike drug names. About 12% of oxytocin errors reported to ISMP described name confusion between Pitocin and Pitressin, a long-discontinued brand of vasopressin originally manufactured by Parke-Davis (now a division of Pfizer). While some of these reports were received more than a decade ago, errors have persisted because vasopressin is sometimes still referred to as “PIT” or “Pitressin,” and the drug name can still be found in some order entry systems (see THEME 1). Most of the reported errors   involved verbal orders or requests to the pharmacy for “Pitressin” that were misheard as Pitocin. The few errors in which “Pitressin” infusions were dispensed instead of the intended Pitocin infusion resulted in harm (e.g., pulmonary edema).

THEME 3:  PREPARATION CHALLENGES

Preparation and/or labeling problems. Nurses may prepare oxytocin infusions on the patient care unit, just before use, by withdrawing the medication from a vial and adding the appropriate volume to a bag of IV solution (e.g., 0.9% sodium chloride). The diluted solution is then administered IV via an infusion pump. Nursing admixture on a patient care unit risks sterility and preparation errors. Also, if a nurse-prepared IV infusion bag is not labeled legibly, completely, and accurately, it can be indistinguishable from bags containing plain IV solutions. This multi-organization analysis highlighted cases in which incomplete or omitted labels on nurse-prepared infusions led to patient safety issues. These labeling problems were typically due to interruptions, distractions, or competing priorities on the patient care unit.

An unlabeled bag of what was presumed to be a plain IV solution was administered to a patient. Staff later noted maternal cramping and fetal heart rate deceleration. An investigation revealed that the bag contained oxytocin. The patient required an emergency cesarean section.

THEME 4:  ADMINISTRATION-ASSOCIATED ERRORS

Infusion pump or IV line mix-ups. Mix-ups of IV lines and misconnections to the wrong infusion pump have resulted in drug or dose errors and omissions. Contributing factors included the need for multiple IV lines, a fast-paced work environment, heavy workload, failure to trace lines, inexperienced staff, and distractions. 

During augmentation of labor, IV oxytocin was to be administered at a controlled, prescribed rate via an infusion pump, while IV Lactated Ringer’s was to be administered rapidly via gravity. During the set-up process, the lines were mixed up, and the oxytocin solution was inadvertently left to run freely without a pump. As a result, the patient received a larger-than-intended dose of oxytocin, an error that led to the need for a cesarean section.

Infusion bag swaps. Similar to line mix-ups, numerous errors were reported in which an oxytocin infusion bag was mixed up with either a hydrating fluid or magnesium infusion, leading to significant under- or overdoses. A common contributing factor included availability of an oxytocin infusion during labor that was intended for use postpartum.

For a laboring mother who was progressing well, a nurse selected what she thought was an infusion bag containing 500 mL of Lactated Ringer’s but was actually oxytocin (30 units/500 mL). The mother received an unspecified amount of oxytocin prior to delivery at an infusion rate normally used for hydrating fluids. The oxytocin infusion had been prepared for use after delivery and had been brought into the labor room by a second nurse. Shortly after oxytocin administration began, the mother’s contractions intensified, and fetal monitoring demonstrated significant heart rate decelerations. The baby was delivered as soon as possible and had a low Apgar score without spontaneous breathing, requiring admission to the neonatal intensive care unit.  

Failure to scan the barcode on the infusion bag, often due to a sense of urgency, was another contributing factor. 

After a precipitous birth, a mother was prescribed a bolus dose and continuous infusion of oxytocin to alleviate postpartum bleeding. A nurse quickly gathered what she thought was an oxytocin infusion but did not scan the bag’s barcode prior to hanging the infusion. An hour after starting the infusion, the mother experienced hypotension, weakness, and vomiting and was given a dose of IV ondansetron. Later, when the nurse was hanging a replacement bag of oxytocin, she noticed that the initial infusion bag contained magnesium (20 g/500 mL), not oxytocin (30 units/500 mL). The mother’s magnesium toxicity was treated with IV calcium gluconate with improvement in symptoms.

Infusion rate confusion. Inconsistent terminology used to express an oxytocin infusion rate in the medication order, administration record, and/or pump library led to several errors. The concentration of oxytocin in an IV infusion solution is usually expressed in milliunits per mL or units per L. The administration rate for the solution is typically expressed as the amount of drug (milliunits/minute) and as the volume of solution to be infused (e.g., mL/hour). As a result of confusion between the units of measure, infusion pump programming errors were made, which resulted in the delivery of more than the intended dose of oxytocin.

Inadvertent bolus doses from leftover drug in tubing. One reported event reminded us how residual oxytocin (or other drugs) in IV tubing can have severe adverse effects when other medications or infusions are administered through the same line. If IV lines are not changed, the length of the IV tubing may contain 10 mL or more of uninfused drug. Additionally, needleless ports and stopcocks also have dead space where the drug can accumulate.

Residual oxytocin left in an obstetrical patient’s IV line caused hypertonic, tetanic uterine contractions leading to deceleration of the fetal heart rate and fetal hypoxia, when a Lactated Ringer’s hydrating solution was rapidly infused through the same IV line.

THEME 5:  COMMUNICATION GAPS

Incomplete hand-offs at transitions of care. The lack of clear communication and/or documentation during transitions of care was a key contributor to oxytocin incidents. Reporters attributed poor communication/documentation to heavy workload, a fast-paced environment, inexperience, and involvement of many individuals in the patient’s care.

Administration of oxytocin was put on hold when staff noted a deceleration in the fetal heart rate. Fifteen minutes later, the physician examined the patient and gave a verbal order to restart the oxytocin infusion, but at a lower rate. A few minutes later, a second physician, who was taking over for the first, gave an order to restart the oxytocin at the original dose. The lack of documentation regarding the decision to lower the rate of infusion was considered to be a factor in this incident.

SAFE PRACTICE RECOMMENDATIONS: Form an interdisciplinary team and consider the following recommendations as you plan, implement, and monitor the effectiveness of strategies to mitigate the risk of oxytocin errors and associated maternal, fetal, or neonatal harm.

Increase the number of drug name letters required in electronic searches. ISMP recommends requiring a minimum of 5 letters when searching for a drug name  in electronic systems (see #19 in the ISMP Guidelines for Safe Electronic Communication of Medication Information), resulting ideally in only one drug name appearing in the results field. Indication-based prescribing could also support the correct selection and appropriate use of medications.

Employ standard order sets. Require the use of standard order sets for prescribing oxytocin antepartum and/or postpartum that reflect a standardized clinical approach to labor induction/augmentation and control of postpartum bleeding. Include administration requirements, patient monitoring, standard treatment of oxytocin-induced uterine tachysystole,² and other safety measures. (Use of standard order sets will also reduce drug selection errors during prescribing.)

Standardize concentration/bag size. Standardize to a single concentration/bag size for both antepartum and postpartum oxytocin infusions (e.g., 30 units of oxytocin in 500 mL of Lactated Ringer’s^2,3).

Provide oxytocin in ready-to-use form. Provide patient care units with ready-to-use IV bags of oxytocin in a standardized concentration that are pharmacy-prepared or from an outsourced sterile compounding service to avoid the need for drug manipulation at the bedside. Before distribution of the bags to patient care units, boldly label both sides of the bags to differentiate them from plain hydrating solutions and magnesium infusions. If oxytocin infusions must be prepared on patient care units during an emergency, require an independent double check of the preparation and provide preprinted labels to affix to prepared bags.

Standardize dosing units. Standardize how oxytocin doses, concentrations, and rates are expressed. Always communicate orders for oxytocin infusions in terms of the dose rate (e.g., milliunits/minute) to lessen the opportunity for misinterpretation. Align oxytocin dosing units and concentration with the smart pump dose error-reduction system.

Employ barcode scanning technology. Despite a fast-paced environment of care, require the scanning of barcodes on oxytocin vials and infusion bags prior to preparation, dispensing, stocking (e.g., in ADCs), and administration to help ensure that the right product has been selected.

Use smart infusion pumps. Deliver all IV oxytocin via smart infusion pumps with an engaged dose error-reduction system. Bi-directional smart pump interoperability with the electronic health record will also reduce the risk of programming errors.

Label and trace lines. Label the IV tubing on oxytocin infusions just above the injection port closest to the patient and just above the pump. When setting up an infusion, trace the line from the infusion bag to the pump, and from the pump to the patient (and/or vice versa), to ensure the correct line attachment. Independent double checks can be used to verify the setup of IV lines.

Conduct vial/infusion bag packaging assessment. Prior to use (or purchase) of medication vials or premixed infusion bags, conduct an assessment to ensure they do not look similar to other vials or bags used in the facility and that the label is clear regarding the amount of drug per total volume. This process should occur even for a drug that is used temporarily during a drug shortage or other reason. If similarities are noticed, and the drug/solution cannot be purchased from a different manufacturer/supplier, implement strategies to avoid confusion (e.g., auxiliary labeling on vials, infusion bags, bins, ADC screens) and warn all users about the risk. 

Store separately. Separate the storage of look-alike oxytocin and ondansetron vials (and other look-alike vials) in the pharmacy and patient care storage locations. Try to obtain one of the products from a different manufacturer and utilize barcode scanning.

Reduce access to unneeded medications. Whenever possible, avoid bringing any medication or solution to the patient’s bedside until it is prescribed and needed. Restricting access to unneeded medications is a key error-reduction strategy, particularly in birthing units where emergent circumstances may require rapid changes in the plan of care.

Avoid outdated brand names and drug name abbreviations. Remove outdated brand names, including Pitressin, from CPOE systems. Avoid using abbreviations such as “PIT” for either Pitocin or Pitressin or “OXY” for oxytocin or oxyCODONE/OxyCONTIN. 

Limit verbal orders. Limit verbal orders to emergencies or under sterile conditions. When they are needed, readback (or repeat back under sterile conditions) is a must.

Discard discontinued bags and change oxytocin tubing. When an oxytocin infusion is discontinued, promptly remove and discard any unused portion of the infusion and change the IV line to ensure no residual drug is left in the tubing.

Support clear communication/documentation. Use standardized communication strategies (e.g., SBAR) and documentation tools during transitions of care to promote clear, timely, and efficient exchange of patient information.

Engage patients. Encourage questions about oxytocin to further engage patients/families in the birth planning process.

References

1. ISMP Canada. Errors associated with oxytocin use: a multi-incident analysis. ISMP Canada Safety Bulletin. 2019;19(8):1-5. 
2. Simpson KR, Knox GE. Oxytocin as a high-alert medication: implications for perinatal patient safety. MCN Am J Matern Child Nurs. 2009;34(1):8-15.
3. McKenna DS, Rudinsky K, Sonek J. Effects of a new patient safety-driven oxytocin dosing protocol on postpartum hemorrhage. J Pregnancy. 2014;2014:157625.

ISMP thanks ISMP Canada for providing the analysis of oxytocin events reported in Canada.¹