Updated on: September 23, 2013

ICD-10 Inpatient Case Study: Congenital Brain Anomaly

Original story posted on: December 1, 2011

Below is a case study that identifies some of the subtle differences between the descriptions of ICD-9-CM and ICD-10 codes. Note that the ICD-10 codes provide a higher level of specificity to the code assignment.


Postoperative diagnosis: Colloid cyst of the third ventricle


Operation: Bi-frontoparietal craniotomy, transcallosal removal of colloid cyst under the operating microscope


Anesthesia: General


Description of Operation: Under general endotracheal anesthesia, the patient was placed supine with the head held in a Sugita headrest. Registration of the Stryker navigation system was done with fiducials on the head and the head then prepped and draped in the usual sterile manner. A bicoronal incision was made and the scalp flap reflected anteriorly. A free bone flap was elevated with power drill and craniotome. This was extended from slightly posterior to the coronal suture for approximately 5 cm and primarily to the right side but did go slightly across the midline to the left. The dura was then opened and tacked and held back with stay sutures.


Under the operating microscope, an interhemispheric approach was made down to the corpus callosum.  The pericallosal vessels were separated and an incision made in the corpus callosum into the lateral ventricle. Our initial approach was into the left lateral ventricle and explored the foramen of Monroe and did not initially see the colloid cyst. I coagulated the choroid plexus at the foramen of Monroe and, by gently removing this, located a bulging thin layer of fibrinous tissue under which the colloid cyst was found. The cyst was opened. Cyst contents were removed and then with microdissection around the capsule, the capsule was fully removed.  Hemostasis was then achieved.  The dura was closed with a Bovie pericardial graft.  The bone flap was secured in place with Lorenz plates and bur hole covers and the scalp closed in layers in the usual manner and sterile dressing applied.


Code Assignments

Listed in the table below is a comparison of the ICD-9-CM and ICD-10-CM diagnosis codes for this procedure. The descriptions of this condition are similar; however, the ICD-10-CM description is more specific, identifying the condition as cerebral cysts, which the physician documented.


ICD-9-CM Diagnosis Coding

ICD-10-CM Diagnosis Coding

742.4 Congenital anomaly of brain

Q04.6 Congenital cerebral cysts


As we all know by now, each character of the ICD-10-CM code is a specific identifier:


Q = Chapter 17: Congenital Malformations, Deformations and Chromosomal Abnormalities; 04 = other congenital malformations of brain; and .6 = congenital cerebral cysts.


In the ICD-10-CM code book, locate the term “cyst” in the index, followed by the term “brain” and look down to the terms of “third ventricle (colloid), congenital” to obtain the code Q04.6. Then check the code in the tabular listing to ensure that no further character is required to completely report the code.


Now review the second table, which lists the ICD-9 procedure codes, against the ICD-10 procedure codes, and you will see that their descriptors differ. The ICD-10-PCS code provides the specificity to the area of the brain where the excision occurred. The ICD-9-CM code documents only that the excision was somewhere in the brain.


Starting with the term “excision” in the ICD-10-PCS Index, do not look for the term “cyst” under excision, because it is not there. Remember the root operation of “excision” is to remove all or part of an organ, so you are looking for the site of the excision; in this case cerebral ventricle.  You will find 00B6.  From there, go into the Table for 00B6 to complete the code assignment.


ICD-9-CM Procedure Coding

ICD-10-PCS Procedure Coding

01.59 Excision/destruction of lesion/tissue of brain

00B60ZZ Excision of cerebral ventricle, open approach



Like the ICD-10 diagnosis codes, each digit in the ICD-10-PCS column identifies a specific feature: 0 = medical and surgical; 0 = anatomical region, brain; B = excision; 6 = cerebral ventricle; 0 = open approach; Z = no device; and Z = no qualifier.


The last character of the code is reported as “no qualifier” vs. “diagnostic” as the entire cyst was removed.


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About the Author

Susan Howe is a senior healthcare consultant with Medical Learning, Inc., St. Paul, MN.


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